Question 1

The assembly time for a product is uniformly distributed between 6 to 10 minutes.The probability of assembling the product in 7 minutes or more is

Accepted Answer

A)  0.25 
B)  0.75 
C)  zero 
D)  1

Question 2

The assembly time for a product is uniformly distributed between 6 to 10 minutes.The probability of assembling the product between 7 to 9 minutes is

Accepted Answer

A)  zero 
B)  0.50 
C)  0.20 
D)  1

Question 3

Given that z is a standard normal random variable, what is the value of z if the area between -z and z is 0.901?

Accepted Answer

A)  1.96 
B)  -1.96 
C)  $\pm$ 0.4505 
D)  $\pm$ 1.65

Question 4

The function that defines the probability distribution of a continuous random variable is a

Accepted Answer

A)  normal function. 
B)  uniform function. 
C)  either normal of uniform depending on the situation. 
D)  probability density function.

Question 5

The assembly time for a product is uniformly distributed between 6 to 10 minutes.The expected assembly time (in minutes) is

Accepted Answer

A)  16 
B)  2 
C)  8 
D)  4

Question 6

When a continuous probability distribution is used to approximate a discrete probability distribution, a value of 0.5 is

Accepted Answer

A)  added to and/or subtracted from the area. 
B)  added to and/or subtracted from the value of x. 
C)  added to and/or Subtracted from the value of z. 
D)  added to and /or subtracted from the value of µ.

Question 7

The weight of football players is normally distributed with a mean of 200 pounds and a standard deviation of 25 pounds.What percent of players weigh between 180 and 220 pounds?

Accepted Answer

A)  28.81% 
B)  0.5762% 
C)  0.281% 
D)  57.62%

Question 8

A professor at a local university noted that the exam grades of her students were normally distributed with a mean of 73 and a standard deviation of 11.Students who made 57.93 or lower on the exam failed the course.What percent of students failed the course?

Accepted Answer

A)  8.53% 
B)  18.53% 
C)  91.47% 
D)  0.853%

Question 9

For a continuous random variable x, the probability density function f(x) represents

Accepted Answer

A)  the probability at a given value of x. 
B)  the area under the curve at x. 
C)  the area under the curve to the right of x. 
D)  the height of the function at x.

Question 10

The travel time for a college student traveling between her home and her college is uniformly distributed between 40 and 90 minutes.The probability that her trip will take exactly 50 minutes is

Accepted Answer

A)  zero 
B)  0.02 
C)  0.06 
D)  0.20

Question 11

The time it takes to travel from home to the office is normally distributed with $\mu$ = 25 minutes and  = 5 minutes.What is the probability the trip takes more than 20 minutes?

Accepted Answer

A)   .1587 
B)  .3333 
C)   .6667 
D)   .8413

Question 12

A standard normal distribution is a normal distribution with

Accepted Answer

A)  a mean of 1 and a standard deviation of 1. 
B)  a mean of 0 and a standard deviation of 0. 
C)  any mean and a standard deviation of 1. 
D)  a mean of 0 and standard deviation of 1.

Question 13

For any continuous random variable, the probability that the random variable takes a value less than zero

Accepted Answer

A)  is any number between zero and one. 
B)  is more than one, since it is continuous. 
C)  is a value larger than zero. 
D)  is zero.

Question 14

There is a lower limit but no upper limit for a random variable that follows the

Accepted Answer

A)  ​uniform probability distribution. 
B)  ​normal probability distribution. 
C)  ​exponential probability distribution. 
D)  ​binomial probability distribution.

Question 15

x is a normally distributed random variable with a mean of 12 and a standard deviation of 3.The probability that x equals 19.62 is

Accepted Answer

A)  0.000 
B)  0.0055 
C)  0.4945 
D)  0.9945

Question 16

The assembly time for a product is uniformly distributed between 6 to 10 minutes.The standard deviation of assembly time (in minutes) is approximately

Accepted Answer

A)  1.3333 
B)  1.1547 
C)  0.1111 
D)  0.5773

Question 17

z is a standard normal random variable.The P(-1.96 $\leq$ z $\leq$ -1.4) equals

Accepted Answer

A)  0.8942 
B)  0.0558 
C)  0.475 
D)  0.4192

Question 18

Which of the following is a characteristic of the standard normal probability distribution?

Accepted Answer

A)  The mean, median, and the mode are not equal 
B)  The distribution is not symmetrical 
C)  The standard deviation must be 0 
D)  The standard deviation must be 1

Question 19

The probability that a continuous random variable takes any specific value

Accepted Answer

A)  is equal to zero. 
B)  is at least 0.5. 
C)  depends on the probability density function. 
D)  is very close to 1.0.

Question 20

Which of the following is not a characteristic of the normal probability distribution?

Accepted Answer

A)  Symmetry 
B)  The total area under the curve is always equal to 1. 
C)  99.72% of the time the random variable assumes a value within plus or minus 1 standard deviation of its mean 
D)  The mean is equal to the median, which is also equal to the mode.

Exam 6: Continuous Probability Distributions