



a. 
P(Z > 0.74) 

b. 
P(Z ≤ −1.92) 

c. 
P(0 ≤ Z ≤ 1.62) 

d. 
P(−0.90 ≤ Z ≤ 2.94) 






a. 
P(X > 10) 

b. 
P(X > 20) 

c. 
P(10 < X < 20) 



a. 
Find P(X ≤ 86). (Round "z" value to 2 decimal places and final answer to 4 decimal places.) 
P(X ≤ 86) 

b. 
Find P(80 ≤ X ≤ 100). (Round "z" value to 2 decimal places and final answer to 4 decimal places.) 
P(80 ≤ X ≤ 100) 

c. 
Find x such that P(X ≤ x) = 0.40. (Round "z" value to 2 decimal places and final answer to nearest whole number.) 
x 

d. 
Find x such that P(X > x) = 0.90. (Round "z" value to 2 decimal places and final answer to 1 decimal place.) 
x 


a. 
Find P(X > 7.6). (Round "z" value to 2 decimal places and final answer to 4 decimal places.) 
P(X > 7.6) 

b. 
Find P(7.4 ≤ X ≤ 10.6). (Round "z" value to 2 decimal places and final answer to 4 decimal places.) 
P(7.4 ≤ X ≤ 10.6) 

c. 
Find x such that P(X > x) = 0.025. (Round "z" value and final answer to 2 decimal places.) 
x 

d. 
Find x such that P(x ≤ X ≤ 2.5) = 0.4943. (Negative value should be indicated by a minus sign. Round "z" value and final answer to 2 decimal places.) 
x 





a. 
P(Z ≤ z) = 0.9744 

b. 
P(Z > z) = 0.8389 

c. 
P(−z ≤ Z ≤ z) = 0.95 

d. 
P(0 ≤ Z ≤ z) = 0.3315 


Exhibit 61. You are planning a May camping trip to Denali National Park in Alaska and want to make sure your sleeping bag is warm enough. The average low temperature in the park for May follows a normal distribution with a mean of 32°F and a standard deviation of 8°F.
Refer to Exhibit 61. One sleeping bag you are considering advertises that it is good for temperatures down to 25°F. What is the probability that this bag will be warm enough on a randomly selected May night at the park?
0.8800 

0.8106 

0.1894 

0.3106 
It is known that the length of a certain product X is normally distributed with μ = 20 inches. How is the probability related to ?
\ is the same as \. 

\ is smaller than \. 

No comparison can be made with the given information. 

\ is greater than \. 
Let X be normally distributed with mean μ and standard deviation σ > 0. Which of the following is true about the z value corresponding to a given x value?
A positive z = (x  μ)/σ indicates how many standard deviations x is above μ. 

All of the above. 

A negative z = (x  μ)/σ indicates how many standard deviations x is below μ. 

The z value corresponding to x = μ is zero. 
Find the probability P(1.96 ≤ Z ≤ 0).
0.0250 

0.4750 

0.5250 

0.0500 
The probability that a normal random variable is less than its mean is ___.
1.0 

Cannot be determined 

0.0 

0.5 
How many parameters are needed to fully describe any normal distribution?
2 

1 

3 

4 
The time to complete the construction of a soapbox derby car is normally distributed with a mean of three hours and a standard deviation of one hour. Find the probability that it would take between 2.5 and 3.5 hours to construct a soapbox derby car.
0.3085 

0.6170 

0.3830 

0.6915 
Let X be normally distributed with mean µ = 250 and standard deviation σ = 80. Find the value x such that P(X ≤ x) = 0.9394.
126 

1.55 

374 

1.55 
Exhibit 62. Gold miners in Alaska have found, on average, 12 ounces of gold per 1000 tons of dirt excavated with a standard deviation of 3 ounces. Assume the amount of gold found per 1000 tons of dirt is normally distributed.
Refer to Exhibit 62. What is the probability the miners find more than 16 ounces of gold in the next 1000 tons of dirt excavated?
0.5918 

0.0918 

0.9082 

0.4082 
Top of Form
If X has a normal distribution with and , then the probability can be expressed in terms of a standard normal variable Z as _______.







Round "z" value to 2 de...