For randomly selected adults, IQ scores are normally distributed with a standard deviation of 15. The scores of 14 randomly selected college students are listed below. Use a 0.10 significance level to test the claim that the standard deviation of IQ scores of college students is less than 15. Round the sample standard deviation to three decimal places. 115 128 107 109 116 124 135 127 115 104 118 126 129 133
Answers
STEP 1: Work out the mean of data set
μ = Sum of values in the set ÷ Number of values in the set
μ = 1686 ÷ 14
μ = 120.4 (rounded to one decimal place)
STEP 2: Subtract the mean from each value in the data set, and then square each answer. The table attached below shows the details of the calculation
STEP 3: Add the answers in STEP 2, then divide by 13.
Note: we divide by 13 instead of 14 because our data set is a sample set.
(∑x₁-μ)/13 = 1253.44÷13 = 96.42
The value obtained in STEP 3 is the variance. To obtain the standard deviation, we square root the variance
s = √96.42 = 9.819 (rounded to three decimal places)
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We want to test the claim that the standard deviation of IQ scores of college students is less than 15. Putting this in the form of hypotheses we get:
H₀: σ=15
H₁: σ<15
The significance level, α, is 0.10
The degrees of freedom, v, is 14 - 1 = 13
Reading from the Chi² table for α = 0.1 and degree of freedom = 13, we have the critical value ≥19.812
The value of the test statistic is given as [(n-1)²s²] ÷ σ²
We have n = 14, s = 9.819, and σ = 15
test statistic = [(13)²(9.819)²] ÷ 15² = 72.417
72.417 is in the critical region (which is values ≥ 19.812) so the result is significant and H₀ is rejected. The standard deviation of IQ scores of college students is less than 15.
To test if the standard deviation of college students' IQ scores is less than 15, we must calculate the sample standard deviation and then perform a chi-square test for variance. Comparing the test statistic to the chi-square distribution at a 0.10 significance level allows us to accept or reject the null hypothesis.
Explanation:To test the claim that the standard deviation of IQ scores of college students is less than 15, we first need to calculate the sample standard deviation. The scores provided are 115, 128, 107, 109, 116, 124, 135, 127, 115, 104, 118, 126, 129, 133. We find the mean of these scores and then use the formula for sample standard deviation.
Step 1: Calculate the mean of the IQ scores.
Step 2: Find the sum of the squared deviations of each score from the mean.
Step 3: Divide by the number of scores minus one (n-1) to get the variance.
Step 4: Take the square root of the variance to find the sample standard deviation.
Once we have the sample standard deviation, we use the chi-square test for variance since we are testing about the population variance. Under the null hypothesis, we assume that the population standard deviation is 15. At a significance level of 0.10, we compare the test statistic to the corresponding chi-square distribution to determine if we can reject the null hypothesis.
Related Questions
4. Meagan invests $1,200 each year in an IRA for 12 years in an account that earned 5%
compounded annually. At the end of 12 years, she stopped making payments to the
account, but continued to invest her accumulated amount at 5% compounded annually for
the next 11 years.
a. What was the value of the Ira at the end of 12 years?
b. What was the value of the investment at the end of the next 11 years?
c. How much interest did she earn?
Answers
[tex]\bf \qquad \qquad \textit{Future Value of an ordinary annuity}\\ \left. \qquad \qquad \right.(\textit{payments at the end of the period}) \\\\ A=pymnt\left[ \cfrac{\left( 1+\frac{r}{n} \right)^{nt}-1}{\frac{r}{n}} \right][/tex]
[tex]\bf \qquad \begin{cases} A= \begin{array}{llll} \textit{accumulated amount}\\ \end{array} \begin{array}{llll} \end{array}\\ pymnt=\textit{periodic payments}\to &1200\\ r=rate\to 5\%\to \frac{5}{100}\to &0.05\\ n= \begin{array}{llll} \textit{times it compounds per year}\\ \textit{annually, thus once} \end{array}\to &1\\ t=years\to &12 \end{cases}[/tex]
[tex]\bf A=1200\left[ \cfrac{\left( 1+\frac{0.05}{1} \right)^{1\cdot 12}-1}{\frac{0.05}{1}} \right]\implies A\approx 19100.55[/tex]
part B)
so, for the next 11 years, she didn't make any deposits on it and simple let it sit and collect interest, compounded annually at 5%.
[tex]\bf \qquad \textit{Compound Interest Earned Amount} \\\\ A=P\left(1+\frac{r}{n}\right)^{nt} \ \begin{cases} A=\textit{accumulated amount}\\ P=\textit{original amount deposited}\to &\$19100.55\\ r=rate\to 5\%\to \frac{5}{100}\to &0.05\\ n= \begin{array}{llll} \textit{times it compounds per year}\\ \textit{annually, thus once} \end{array}\to &1\\ t=years\to &11 \end{cases} \\\\\\ A=19100.55\left(1+\frac{0.05}{1}\right)^{1\cdot 11}\implies A\approx 32668.42[/tex]
part C)
well, for 12 years she deposited 1200 bucks, that means 12 * 1200, or 14,400.
now, here she is, 12+11, or 23 years later, and she's got 32,668.42 bucks?
all that came out of her pocket was 14,400, so 32,668.42 - 14,400, is how much she earned in interest.
a. The value of the Ira at the end of 12 years is $19,100.55.
b. The value of the investment at the end of the next 11 years is $32,668.43.
c. Interest earn is $18,288.43.
a. Using this formula to determine the value of the Ira at the end of 12 years
A=Pmt [(1+r)^n-1]/r
Let plug in the formula
A=1,200[(1+0.05)^12-1]/0.05
A=1,200[(1.05)^12-1]/0.05
A=$1,200(0.795856)/0.05
A=$955.02759/0.05
A=$19,100.55
b. The value of the Ira at the end of 11 years is:
$19,100.55(1+0.05)^11
=$19,100.55(1.05)^11
=$19,100.55(1.710339358)
=$32,668.43
c. Interest earn
Total investment=1200(12)
Total investment= $14,400
Now let calculate the interest earned
Interest earned = $32,668.43 - $14,400
Interest earned= $18,288.43
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Bob drove from home to work at 50 mph. After work the traffic was heavier, and he drove home at 30 mph. His driving time to and from work was 1 hour and 4 minutes. How far does he live from his job?
Answers
The formula we need to solve this problem is:
Distance = Speed * Time
2.
Bob traveled the distance from work to his house at 30 mph, for 1 hour 4 minutes.
let's convert 1 hour 4 minutes to hours.
60 minutes are 1 hour
so 4 minutes are (4 minutes *1 hour)/ (60 minutes)= 0.067 hour.
Thus 1 hour 4 minutes = 1.067 h
The distance is Speed*Time= 30 mph*1.067 h=32.01 m
Answer: 32.01 miles
Savings account A and savings account B both offer APRs of 7%, but savings account A compounds interest quarterly, while savings account B compounds interest semiannually. Which savings account offers the higher APY? A. Savings account A, because it has more compounding periods per year B. Savings account B, because it has fewer compounding periods per year C. Savings account A, because it has fewer compounding periods per year D. Savings account B, because it has more compounding periods per year @countonme123 @ganeshie8
Answers
Answer:
The answer is Savings account B
Savings account A offers a higher APY because it compounds quarterly, which is more frequent than savings account B which compounds semiannually. More compounding periods per year lead to interest being earned on interest more often, resulting in a higher effective yield.
Annual Percentage Yield (APY) given that both accounts offer the same Annual Percentage Rate (APR) of 7%, but one compound quarterly and the other semiannually. The APY is a measure of how much interest an account will earn in a year, taking into account the effect of compounding.
Compounding more frequently results in a higher yield because interest is earned on interest more often. Account A compounds quarterly, meaning it does so four times a year, while Account B compounds semiannually, meaning it does so twice a year. As the frequency of compounding increases, so does the APY, because the money earns interest on the interest that has been added to the account more frequently.
Therefore, the correct answer is A. Savings account A, because it has more compounding periods per year, which means it will have a higher APY compared to savings account B which compounds less frequently.
Find x. Round your answer to the nearest tenth of a degree.
Answers
Answer:
x=49,6323º
Step-by-step explanation:
To solve this you just have to use the inverted sin X, remember that Sin=opposite/hyphotenuse
Sinx= 16/21
Sin x=,761904
x=-1Sin,761904
x=49,6323
So the measure of the angle X would be 49,6323.
someone help me. Not good at math
Answers
perimeter = add all 3 sides 13+13+10 = 36 cm
for area you need to find the height of the triangle, which is the red dotted line
to do that use the Pythagorean Theorem
a^2 + B^2= c^2
a^2 = height
a^2 +5^2 = 13^2
a^2 +25 = 169
a^2 = 169-25 = 144
a=square root(144) = 12
so the height is 12
area = 1/2 h x b = 1/2 x 12 x 10 = 1/2x 120 = 60
area = 60 cm^2
cost is $4 per square cm
there is 60 square cm in the triangle so multiply 60 x 4 = $240
Find the mean, variance, and standard deviation of the binomial distribution with the given values of n and p.
n=128,
p=0.27
The mean is ______
. (Round to the nearest tenth as needed.)
The variance,
σ^2 is ______
(Round to the nearest tenth as needed.)
The standard deviation, ______
Answers
A binomial distribution is an experiment where there are two outcomes; Success and failure. In here, you are given n = 128 and p = 0.27. The formula for the variance of a binomial distribution is n*p(1 – p) or n*p*q*. They are equivalent because q = 1- p. We will use the first equation.
Variance = n*p*(1 – p)
Variance = 128*0.27*(1 – 0.27)
Variance = 25.23
To get the standard deviation, find the square root of the variance.
Standard deviation = sqrt (Variance)
Standard deviation = sqrt (25.23)
Standard deviation = 5.02
A moving company charges 0.60 per pound for a move from New York to Florida. A family estimates that their belongings weigh about 4 tons. About how much would it cost the family to move from New York to Florida?
Answers
so 4 tons = 4 * 2000 = 8000 lbs
at 0.60 per lb...
8000(0.6) = $ 4800 <==
how much does one pepper cost if they are priced three for 2.07
Answers
One pepper cost is 0.69.
What is Selling price?
Selling price is defined as the price that a customer pays to purchase a product.
Let one pepper cost is x,
Three peppers cost is 2.07,
x = ratio of the total cost of peppers to the number of peppers .
x= 2.07/3
x = 0.69
So, the peppers cost 69 cents each.
Hence, one pepper cost is 0.69.
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Margaret plans to deposit $500 on the first day of each of the next five years, beginning today. if she earns 4% compounded annually, how much will she have at the end of five years?
Answers
Deposits: = $ $3,424.81
Interest Earned: $424.81
The question is unclear, I calculated $500 yearly deposit with the compound.
Stella is renting a car for a business trip. The agency charges a flat rate of $60 plus $0.50 per mile every mile she drives over 40 miles. Stella's company will pay up to $270, excluding the cost of gasoline , for the use of the rental car. What is the number of miles Stella can drive the rental car without spending more then$270
Answers
270 =60 + 0.50(x-40)
270 =60 + 0.50x -20
210 =0.50x -20
230=0.50x
x=230/0.50 = 460 miles
check:
460-40 = 420
420*0.50=210 +60=270
she can drive 460 miles total
A balloon is released and flies straight up for 120 feet, and then the wind blows it east for 280 feet. Find the distance between the balloon and the site where it was released. Decimal rounded one place.
Answers
The distance between the balloon and the site where it was released will be the hypotenuse of such triangle, so you can use Pythagorean theorem to find the distance.
c^2 = (120ft)^2 + (280ft)^2 = 78400 ft^2
=> c = √ (78400 ft^2) = 280 ft
Answer: 280 ft
A store is offering a 20% discount on all sales over $50 if you purchase a T-shirt and a pair of jeans for $62.50 what is the amount of the discount you would receive
Answers
($62.50*0.2) = 12.5
Therefore, you would get a discount of $12.50. Total price would be $62.50 - $12.50.
The discount on the purchase of a T-shirt and a pair of jeans costing $62.50 with a 20% discount policy is $12.50.
A store's discount policy offers 20% off for purchases over $50. The question involves calculating the discount amount when a T-shirt and a pair of jeans are purchased together for $62.50. To determine the discount, we simply multiply the total purchase amount by the discount rate.
Step-by-Step Calculation:
First, confirm the purchase amount qualifies for the discount. The combined cost of the T-shirt and jeans is $62.50, which is above $50, so the purchase qualifies for the discount.
Calculate the discount by multiplying the total purchase amount by the discount rate: $62.50 × 0.20 (which is the same as 20%).
Discount Amount = $62.50 × 0.20 = $12.50.
Therefore, the amount of the discount the customer would receive on the purchase of the T-shirt and jeans is $12.50.
Which of the following are vertical asymptotes of the function y=3cot(1/2x)-4? A. 3pi B. 2pi C. pi/2 D. 0
Answers
cot is reciprocal of tangent.
cot = 1/tan, Find where tan = 0, since 1/0 goes to infinity.
tan(a) = 0 when a = 0,pi
Now Apply coefficient inside cot function.
x/2 = 0,pi
x = 0, 2pi
Therefore, vertical asymptotes occur when x = 0 or 2pi
Answer:
B and D
Step-by-step explanation:
What is the simplified form of 5 - 4y + 2x - 3y - 2 + 5x?
A. 3 - 7y + 7x
B. 3 + 7y + 7x
C. 7 + 7y + 7x
D. 3 - y + 7x
show steps pls!
Answers
5-2=3
-4y-3y=-7y
2x+5x=7x
Put these combined values together:
3-7y+7x
Final answer: A
To test μ for an x distribution that is mound-shaped using sample size n ≥ 30, how do you decide whether to use the normal or student's t distribution?
Answers
Use the normal distribution if the population standard deviation is known.
Use the student's t distribution when the population standard deviation is unknown.
Explanation:
A mound-shaped distribution refers to the normal distribution.
A good sample size for testing against the normal distribution should be
n >= 30.
The condition for the sample size is satisfied.
However, we are not given the population standard deviation, therefore it is assumed to be unknown.
Therefore the student's t distribution should be used.
whats the equation for
4n + 6 - 2n= 2 (n+3)
Answers
Simplify.
4n + 6 - 2n = 2n + 6
Subtract 6 from both sides.
4n - 2n = 2n + 6 - 6
Subtract 2n from both sides.
4n - 2n - 2n = 6 - 6
Simplify.
0 = 0
Therefore, there are infinite solutions.
~Hope I helped!~
write an expression for the area of the rectangle
Answers
The blades of a windmill turn on an axis that is 40 feet from the ground. The blades are 15 feet long and complete 3 rotations every minute. Write a sine model, y = asin(bt) + k, for the height (in feet) of the end of one blade as a function of time t (in seconds). Assume the blade is pointing to the right when t = 0 and that the windmill turns counterclockwise at a constant rate.
a is the .
The vertical shift, k, is the... length of a blade, height of a windmill, or numbers of rotations per minute.
a =
k =
Answers
The rotational speed is
ω = (3 rev/min)*(1 min/60 s)*(2π rad/rev) = π/10 rad/s
The period is
T = 2π/ω = 20 s
The amplitude of the rotational motion is equal to the radius of 15 ft.
At t=0, the height of the tip of the blade is horizontal to the right, therefore its motion relative to the ground is given by
[tex]y=15 sin( \frac{ \pi t}{10})+40 [/tex]
A plot of the motion is shown below.
20
5
30
Step-by-step explanation:
Evaluate x + sq root(yz) when x = 3, y = 2, and z = –8.
7i
3 + 4i
3 - 16i
3 + 16i
Answers
The value of the expression x + sqrt(yz) when x = 3, y = 2, and z = -8 is 3 + 4i.
Explanation:To evaluate the expression x + sqrt(yz), we substitute the given values for x, y, and z. Given x = 3, y = 2, and z = -8:
x + sqrt(yz) = 3 + sqrt(2*-8) = 3 + sqrt(-16) = 3 + 4i
Therefore, the value of the expression is 3 + 4i.
How many plants x should she plant in each row so that her 25 plants end up in a square (i.e., x plants in each of x rows)?
Answers
5 × 5 = 25
She should plant 5 rows with 5 plants each.
What is a non example of a rate
Answers
Which unit rate is the lowest price per ounce? Choice A: 5 ounces of raisins for $1.49 Choice B: 12 ounces of raisins for $3.59
Answers
Hope this helps
Plz mark as brainliest
A = 1.49/5 =0.298 cents per ounce
B = 3.59/12 = 0.299 cents per ounce
so A has the lowest unit price
At a concert there needs to be at least 1 member of staff working for every 150 members of the audience. If there are 20 members of staff, how many people are in the audience?
Answers
Set a proportion
Staff:Audience
1:150=20:x
x=150•20
x=3000
Answer: There are at most 3,000 people in the audience.
What is the positive root of the equation x 2 + 5x = 150?
Answers
Then factor to (x+15)(x-10)=0
The roots are -15 and 10
The positive root is 10
The positive root of the given quadratic function is x = 10.
How to solve the quadratic function?We have the equation:
[tex]x^2 + 5x = 150[/tex]
First, we rewrite it as:
[tex]x^2 + 5x - 150 = 0[/tex]
Using the Bhaskara's formula, we will get:
[tex]x = \frac{-5 \pm \sqrt{5^2 - 4*(-150)*1} }{2} \\\\x = \frac{-5 \pm 25 }{2}[/tex]
The positive solution is:
x = (-5 + 25)/2 = 10
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Based on the table, which statement best describes a prediction for the end behavior of the graph of f(x)? As x → ∞, f(x) → –∞, and as x → –∞, f(x) → ∞ As x → ∞, f(x) → ∞, and as x → –∞, f(x) → ∞ As x → ∞, f(x) → ∞, and as x → –∞, f(x) → –∞ As x → ∞, f(x) → –∞, and as x → –∞, f(x) → –∞
Answers
Answer: The correct option is B, i.e., "As x → ∞, f(x) → ∞, and as x → –∞, f(x) → ∞".
Explanation:
From the table it is noticed that the first row represents the value of x and the second row represents the value of f(x).
The value of f(x) is 14 at x = -5, after that the value of f(x) is decreased as the value of x increases.
The value of f(x) remains unchanged when the value of x approaches to 0 from 1.
The value of f(x) is -6 at x = 0, after that the value of f(x) is increased as the value of x increases.
From the table it is noticed that as the value of x approaches to positive infinity the value of f(x) is also approaches to positive infinity.
[tex]f(x)\rightarrow\infty \text{ as }x\rightarrow\infty[/tex]
From the table it is noticed that as the value of x approaches negative infinity the value of f(x) is also approaches to positive infinity.
[tex]f(x)\rightarrow\infty \text{ as }x\rightarrow-\infty[/tex]
These statement are shown in second option, therefore the second option is correct.
Answer:
The end behavior of the graph of the function f(x) is:
f(x) → ∞, and as x → –∞, f(x) → ∞ As x → ∞,
Step-by-step explanation:
Based on the table we could observe that the function f(x) is increasing to the left of -1 as well to the right of -1 and it attains the minimum value to be -6.
Hence, it can be predicted that the end behavior of the graph of the function f(x) goes to infinity in the left and also it goes to infinity in the right.
Hence, the statement that best describes the end behavior of the graph of f(x) is:
f(x) → ∞, and as x → –∞, f(x) → ∞ As x → ∞.
Its timed hurry lad
Evaluate the logarithm log8 (32)
Answers
hope that helps
y varies inversely with x k = 1.4 What is the value of x when y is 5.6? A. x = 4 B. x = 1.4 C. x = 0.25 D. x = 7.84
Answers
solve for "x".
What key features of a polynomial can be found using the fundamental theorem of algebra and the factor theorem?
Answers
Answer:
The key fundamental theorem of algebra says that degree of polynomial is equal to number of zeros in a function.The Factor Theorem states that a first degree binomial is a factor of a polynomial function if the remainder, when the polynomial is divided by the binomial, is zero.The winner of a raffle will receive a 21-foot outboard boat. If 6000 raffle tickets were sold and you purchased 30 tickets, what are the odds against your winning the boat?
Answers
Answer: 199: 1.
Step-by-step explanation:
The odds against any event is the ratio of the unfavorable outcomes to the favorable outcomes.
Given , The winner of a raffle will receive a 21-foot outboard boat.
Total raffle tickets were sold = 6000
Number of tickets you have = 30
We assume that the lottery was fair , then, the number of possible outcome that you will win = 30
and the number of possible outcomes that one of the others wins = 6000-30= 5970
Then, the odds against your winning the boat = Number of possible outcomes that one of the others wins : Number of possible outcome that you will win
= 5970: 30 = 199:1 [∵[tex]\dfrac{5970}{30}=\dfrac{199}{1}[/tex]]
Hence, the odds against your winning the boat = 199: 1.
Determine the order in which an inorder traversal visits the vertices of the given ordered rooted tree.
Answers
Explanation:
The left subtree of the root approaches first which is namely the tree rooted at b. There again the left subtree approaches first so the list begins with d. Afterwards that approaches b the root of this subtree and then the right subtree of b specifically in order f, e and g. At that point approaches the root of the whole tree and finally its right child. Thus the answer is d,b,f,e,g,a,c.