An important measure

Question 9
An important measure of the performance of a locomotive is its “adhesion,” which is the locomotive’s pulling force as a multiple of its weight. The adhesion of one 4400-horsepower diesel locomotive model varies in actual use according to a Normal distribution with mean μ = 0.37 and standard deviation σ = 0.04.
What proportion of adhesions measured in use are higher than 0.40? Draw and label the Normal curve and use the standard Normal table.
Select one:

a. 0.1587 

b. 0.2266 

c. 0.7500 

d. 0.7734 



Question 10
Referring to Question 9, what proportion of adhesions are between 0.40 and 0.50? Draw and label the Normal curve and use the standard Normal table.


a. 0.2260 

b. 0.3108 

c. 0.4000 

d. 0.6554 



Question 11

The following situation applies to all remaining questions:

The Wechsler Adult Intelligence Scale (WAIS) is the most common “IQ” test. The scale of scores is approximately Normal with mean 100 and standard deviation 15. What proportion of adults have an IQ less than 90? Draw and label the Normal curve and use the standard Normal table. 


a. –0.67 

b. 0.2514 

c. 0.3707 

d. 0.7486 



Question 12

What is the probability that a randomly selected adult will have an IQ greater than 140? Draw and label the Normal curve and use the standard Normal table. 

a. 0.0038 

b. 0.0267 

c. 0.6064 

d. 0.9962 



Question 13

What is the probability that a randomly selected adult will have an IQ between 130 and 140? Draw and label the Normal curve and use the standard Normal table. 


Select one:


a. 0.0190 

b. 0.4772 

c. 0.6700 

d. 0.7486 



Question 14

What is the IQ that has 90% of the other IQ scores less than it? Draw and label the Normal curve and use the standard Normal table. 


Select one:


a. 0.8159 

b. 19.2 

c. 80.8 

d. 119.2 

e. 130 



Question 15
What is the IQ score that has 20% of the other IQ scores greater than it? Draw and label the Normal curve and use the standard Normal table. 

a. 0.7881 

b. 85.0 

c. 87.4 

d. 112.6 

e. 115.0