Question 1

P( -1 < Z < 1) =

options:

• 0
• 0.95
• 0.68
• 0.997

Question 2

The average salary of a new graduate(X) is $50,000 with a standard deviation of $6,000. If we assume a normal distribution then which of the following is correct?

options:

• X ~ N( 0,1)
• X ~ N ( 50000, 6000)
• X ~ N (6000, 50000)

Question 3

If everyone's salary decreased by 10%. Which of these would change?

options:

• standard deviation
• both mean and standard deviation would NOT change, they would stay the same.
• both mean and standard deviation
• mean

Question 4

it is known that Z~N(0,1)

Find P( 0< Z < 2 ) =

options:

• 2.5%
• 95%
• 27%
• 47.5%
• 68%
• 13.5%

Question 5

the symbol represents:

options:

• population mean
• population standard deviation
• sample standard deviation
• sample mean

Question 6

Round to 4 d.p.

P( Z > 2.47) = [____]

Question 7

Find the Z score for the 75th percentile. Z =

Round Z scores to 2 d.p,

Question 8

Grades are normally distributed with a mean of 75 and a standard deviation of 8. Calculate the Z score of a student who got an 81. Z =

Question 9

Grades are normally distributed with a mean of 75 and a standard deviation of 8.

What is the probability a student passes (60 or higher). P(X>60) = [____] round to 4 d.p.

Question 10

Grades are normally distributed with a mean of 75 and a standard deviation of 8. The top 10% of students scored [____] or higher. round final answer to 1 d.p.