A student takes a 48 question multiple choice quiz. The student is unprepared, so they guess on every question. The probability of guessing a correct answer is 1/4. Find the mean and standard deviation for the random variable

Step-by-step explanation:

Given

Number of questions, n = 48

Probability of correct answer, p = 1/4

Required

- Find the mean

- Find the standard deviation

Using probability notations;

n = 48 and p = 1/4

Mean is calculated as follows;

Substitute 48 for n and 1/4 for p

The Mean is 12

Calculating Standard Deviation (SD)

Substitute 48 for n and 1/4 for p

Solve the expression in the bracket

Open Bracket

Take Square Root of 36

The standard deviation is 6

the answer is 15% decrease

2,600 divided by 80 = 32.5

step-by-step explanation: