A random sample of 100 students had a mean grade point average (GPA) of 3.2 with a standard deviation of 0.2. Calculate an approximate 95% confidence interval for the mean GPA for all students. Note: Assume z-statistics at 95% confidence interval is 2. Report your answer as" ( X.XX - Y.YY) in 2 decimal points.

Answers

Answer 1

Given the above, this means that we are 95% confident that the mean GPA for all students is between 3.20 and 3.20.

What is a confidence interval?

A confidence interval refers to a range of estimates for an unknown variable in frequentist statistics. The 95% confidence level is the most popular, however other levels, such 90% or 99%, are occasionally used when computing confidence intervals.

To calculate an approximate 95% confidence interval for the mean GPA for all students, we need to use the formula for a confidence interval for a population mean:

[tex]$\bar{x} \pm z_{\alpha/2} \frac{\sigma}{\sqrt{n}}$[/tex]

where [tex]$\bar{x}$[/tex][tex]\bar{x}[/tex] is the sample mean, [tex]\sigma[/tex] is the population standard deviation, n is the sample size, and [tex]z_{\alpha/2}[/tex] is the critical value from the standard normal distribution at a confidence level of [tex]\alpha[/tex]

In this case, the sample mean is 3.2, the population standard deviation is 0.2, the sample size is 100, and the critical value at a confidence level of 95% is 2. Therefore, the 95% confidence interval for the mean GPA for all students is:


[tex]$3.2 \pm 2 \frac{0.2}{\sqrt{100}} = (3.20 - 3.20)$[/tex]

This means that we are 95% confident that the mean GPA for all students is between 3.20 and 3.20.

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Related Questions

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Passage
As Ruchira is packing her apartment while preparing to move in with her new husband, Biren, she reflects
on the first time he saw her artwork.
(1) He'd moved close to the wall and was standing very still. (2) It took her a moment to figure out that he
was examining her brushstrokes. (3) (But only artists did that. (4) Was he a closet artist, too?) (5) Finally he
moved back and let out a long, incredulous breath, and it struck her that she had been holding hers as
well. (6) "Tell me about your work," he said.
(7) This was hard. (8) She had started painting two years ago, and had never talked to anyone about it. (9)
Even her parents didn't know. (10) When they came for dinner, she removed the canvases from the wall
and hid them in her closet. (11) She sprayed the room with Eucalyptus Mist and lit incense sticks so they
wouldn't smell the turpentine. (12) The act of painting was the first really risky thing she had done in her
life. (13) Being at the gallery, she knew how different her work was from everything in there, or in the
glossy art journals. (14) Her technique was crude-she hadn't taken classes and didn't intend to. (15) She
would probably never amount to much. (16) Still, she came back from work every evening and painted
furiously. (17) She worked late into the night, light-headed with the effort to remember. (18) She stopped
inviting people over. (19) She made excuses when her friends wanted her to go out. (20) She had to force
herself to return their calls, and often she didn't. (21) She ruined canvas after canvas, slashed them in
frustration and threw them into the Dumpster behind the building. (22) She wept till she saw a blurry
brightness, like sunspots, wherever she looked. (23) Then, miraculously, she got better. (24) Sometimes
now, at 2:00 or 3:00, her back muscles tight and burning, a stillness would rise around her, warm and
vaporous. (25) Held within it, she would hear, word for word, the stories her grandmother used to tell.
From Chitra Banerjee Divakaruni, The Unknown Errors of Our Lives. ©2001 by Chitra Banerjee Divakaruni.
Question
Based on the passage, which of the following best characterizes the outlook of Ruchira's parents on their
daughter's interest in painting?
O They vocally objected to it.
O They admired her commitment to it.
O They were unaware of it.
C They reluctantly accepted it

Answers

Answer:

Explanation:

Based on the passage, it appears that Ruchira's parents are unaware of her interest in painting. This is indicated by several lines in the passage, such as "Even her parents didn't know," "When they came for dinner, she removed the canvases from the wall and hid them in her closet," and "She made excuses when her friends wanted her to go out." These lines suggest that Ruchira is trying to keep her interest in painting a secret from her parents, and that they do not know about her painting or the fact that she has been working on it for two years. This suggests that Ruchira's parents do not have an opinion on her interest in painting, and therefore, the answer is O They are unaware of it.

Ethio engineering Corporation has signed a road construction agreement contract with Ethiopian Road Authority to renew and construct-the main road from Addis Ababw to Diredawa with a contract amount of 250million, 80% of the contract amount will be financed from the loan released by Commercial Bank of Ethiopia at an annual nual interest rate of 13% to be paid as per the following terms of payment At the end of the 1 At the end of the 2 At the end of the 3 At the end of the 4 At the end of the 5th year year year year year At the end of the 6th year 10% of the principal 20% of the principal 30% of the principal 20% of the principal ....15% of the principal 5% of the principal Task 4.1. Determine
A Amount of loan from Commercial Bank Of Ethiopia
B. Amount of Principal and interest repayment for the 20 year
C Amount of outstanding balance at the end of the year including interest expenses
D Total interest of the loan paid all loan ​

Answers

Answer:

A. The amount of the loan from the Commercial Bank of Ethiopia is 250 million x 80% = 200 million.

B. The total amount of principal and interest repayment for the 20-year loan is not specified in the information given. To calculate this, you would need to know the total principal and the total interest over the 20-year period.

C. To calculate the outstanding balance at the end of each year, you would need to know the principal and interest payments made during each year and the annual interest rate. You can then use the following formula:

Outstanding balance = principal + interest - payments

D. To calculate the total interest paid over the 20-year loan period, you would need to know the annual interest rate and the principal. You can then use the following formula:

Total interest = principal x annual interest rate x number of years

Note: These calculations assume that the interest rate is constant throughout the loan period and that the payments are made on schedule. If the interest rate or payments vary, the calculations will be more complex.

Explanation:

The table below shows a student's quiz scores on six quizzes.
Find the mean of this student's quiz scores:
Round to the nearest tenth of a point.
Find this student's median quiz score:
Find the mode of this student's quiz scores:

Answers

Answer:

A) 14,2

B) 15

C) 15

Explanation:

Probability mass function is also known as
Simple mass function
Mass function
Probability density function
Statistical mass function

Answers

Note that the probability mass function is also known as : "Statistical mass function" (Option D)

What is Statistical mass function?

In statistics, the probability mass function is very significant. It specifies the probability for a discrete random variable. It integrates the variable for the supplied random number, which is equal to the random variable's probability.

The difference between a probability mass function and a probability density function (PDF) is that the latter is connected with continuous rather than discrete random variables. To generate a probability, a PDF must be integrated across an interval. The mode is the value of the random variable with the greatest probability mass.

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The population of a particular country consists of three ethnic groups. Each individual belongs to one of the four major blood groups. The accompanying joint probability table gives the proportions of individuals in the various ethnic group–blood group combinations.Blood Group O A B AB 1 .082 .106 .008 .004 Ethnic Group 2 .135 .141 .018 .006 3 .215 .200 .065 .020Suppose that an individual is randomly selected from the population, and define events by , , and . a. Calculate P(A), P(C), and . b. Calculate both and , and explain in context what each of these probabilities represents. c. If the selected individual does not have type B blood, what is the probability that he or she is from ethnic group 1?

Answers

a) The probabilities are given as follows:

P(A): 0.464.P(C): 0.5.P(A and C): 0.203.

b) The conditional probabilities are given as follows:

P(A|C): 0.406.P(C|A): 0.438.

The meaning of each probability is given as follows:

P(A|C): If we know that the individual came from ethnic group 3, the probability that he has type A blood is of P(A|C).P(C|A): If the person has type A blood, the probability that he is from ethnic group 3 is P(C|A).

c) If the selected individual does not have type B blood,  the probability that he or she is from ethnic group 1 is of: 0.225.

How to calculate the probabilities?

A probability is calculated as the division of the number of desired outcomes by the number of total outcomes.

Hence, for item a, the probabilities are calculated from the table given at the end of the answer, as follows:

P(A) = 0.12 + 0.141 + 0.203 = 0.464.P(C) = 0.215 + 0.203 + 0.062 + 0.02 = 0.5.P(A and C) = 0.203. (intersection of the two events in the table).

The conditional probabilities are calculated as follows:

P(A|C): P(A and C)/P(C) = 0.203/0.5 = 0.406.P(C|A): P(A and C)/P(A) = 0.203/0.464 = 0.4375.

The probability that an individual does not have type B blood is given as follows:

1 - 0.005 - 0.018 - 0.062 = 0.915.

The probability that an individual does not have type B blood and is from group 1 is given as follows:

0.082 + 0.12 + 0.004 = 0.206.

Hence the conditional probability for item c is given as follows:

p = 0.206/0.915 = 0.225.

Missing Information

The complete problem is given by the image shown at the end of the answer.

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(b) The mean marks got by 300 students in the subject of statistics are 45. The mean of the top 100 of them was found to be 70 and the mean of the last 100 was known to be 20. What is the mean of the remaining 100 students?​

Answers

Answer: The mean marks of the remaining 100 students is 6000/100= 60.

Explanation: The mean marks of all the students is 45, and the mean marks of the top 100 students is 70, so the sum of the marks of the top 100 students is 70100=7000.

The mean marks of the last 100 students is 20, so the sum of the marks of the last 100 students is 20100=2000.

The sum of the marks of all the 300 students is 7000+2000+45*100=15000.

The sum of the marks of the remaining 100 students is 15000-7000-2000=6000.

The mean marks of the remaining 100 students is 6000/100= 60.

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