Question 1

The number of standard deviations that a value x is from the mean is a(n)____________.

Accepted Answer

A) Variance 
B) Exponential value 
C) z score 
D) Area

Question 2

The first step to constructing a normal probability plot is:

Accepted Answer

A) Calculate Oi 
B) Compute area i/(n + 1) 
C) Construct a box and whiskers plot 
D) Order the values in the data

Question 3

A set of final examination grades in a calculus course was found to be normally distributed with a mean of 69 and a standard deviation of 9.What is the probability of getting a grade of 91 or less on this exam?

Accepted Answer

A) 1.00 
B) 0.50 
C) 0.0073 
D) .9927

Question 4

A student's grade on an examination was transformed to a z value,which was negative.Therefore,we know that he scored:

Accepted Answer

A) Higher than 16 percent of the class. 
B) Higher than 45 percent of the class. 
C) Above the first quartile. 
D) Below the mean. 
E) Lower than 16 percent of the class.

Question 5

If the random variable X has a mean of µ and a standard deviation ?,then (X - µ)/? has a mean and standard deviation respectively:

Accepted Answer

A) ? and ? 
B)  $\bar { X }$
And s 
C) 1 and 0 
D) 0 and 1

Question 6

A set of final examination grades in a calculus course was found to be normally distributed with a mean of 69 and a standard deviation of 9.What percentage of students scored between 65 and 89?

Accepted Answer

A) 65.68% 
B) 100% 
C) 98.68% 
D) 33.00%

Question 7

The mean and median are the same for an exponential distribution.

Accepted Answer

A) True 
 B)False

Question 8

The weight of a product is normally distributed with a standard deviation of .5 ounces.What should the average weight be if the production manager wants no more than 5 percent of the products to weigh more than 5.1 ounces?

Accepted Answer

A) 4.278 
B) 4.409 
C) 3.455 
D) 5.922

Question 9

The relationship between the standard normal random variable z and normal random variable X is that:

Accepted Answer

A) Only the normal random variable X is continuous. 
B) Only the standard normal variable z is continuous. 
C) The standard normal variable z counts the number of standard deviations that the value of the normal random variable X is away from its mean. 
D) The values of the standard normal random variable z cannot be negative. 
E) The values of the normal random variable X cannot be negativE.

Question 10

A set of final examination grades in a calculus course was found to be normally distributed with a mean of 69 and a standard deviation of 9.Only 5 percent of the students taking the test scored higher than what grade?

Accepted Answer

A) 70.04 
B) 67.96 
C) 55.48 
D) 82.52

Exam 6: Continuous Random Variables

The number of standard deviations that a value x is from the mean is a(n) ____________.