×
×

# Using the same SAT questions described in Exercise, find ISBN: 9780321836960 18

## Solution for problem 3CQQ Chapter 5.5

Elementary Statistics | 12th Edition

• Textbook Solutions
• 2901 Step-by-step solutions solved by professors and subject experts
• Get 24/7 help from StudySoup virtual teaching assistants Elementary Statistics | 12th Edition

4 5 0 294 Reviews
21
3
Problem 3CQQ

Using the same SAT questions described in Exercise, find the standard deviation for the numbers of correct answers for those who make random guesses for all 100 questions.

Exercise

There are 100 questions from an SAT test, and they are all multiple choice with possible answers of a, b, c, d, e. For each question, only one answer is correct. Find the mean number of correct answers for those who make random guesses for all 100 questions.

Step-by-Step Solution:
Step 1 of 3

Problem 3CQQ

Step1 of 2:

We have There are 100 questions from an SAT test, and they are all multiple choice with possible answers of a, b, c, d, e. For each question, only one answer is correct. We need to find the mean number of correct answers for those who make random guesses for all 100 questions.

Here,

n =  100

S = {a,b,c,d,e}

Probability of getting correct answer P(correct) =  ⅕

Hence p = ⅕

Step2 of 2:

The mean number of correct answers for those who make random guesses for all 100 questions is given by E(x) = np

= 100 0.20

= 20

Therefore,E(x) = 20 var(x) = npq

= 100 0.20

Step 2 of 3

Step 3 of 3

##### ISBN: 9780321836960

Unlock Textbook Solution