Question

An analysis of the final test scores in this class shows that the scores follow the normal distribution. The mean of the distribution is 85 and the standard deviation is 6. The professor wants to award an A student whose score is in the highest 11% which means 89% of the class will have lower grades. What is the cut-off point (or score) for those students who earn an A versus those that earn a B? In other words, what is the lowest grade an A student can earn? Hint: solve for “x”.

Select one:

a. 92.36

b. 77.64

c. 97.24

d. 96.32

Answer 1

Answer)

As the data is normally distributed we can use standard normal z table to estimate the answers

Z = (x-mean)/s.d

Given mean = 85

S.d = 6

From z table, P(z<1.23) = 89%

So,

1.23 = (x - 85)/6)

X = 92.36

Closest option is

92.38