The scores on an exam are normally distributed, with a mean of 75 and a standard deviation of 5. What percent of the scores are less than 80?

A. 50%

B. 84%

C. 13.5%

D. 16%

B. 84%

Step-by-step explanation:

Given

Mean = π=75

Standard Deviation = σ=5

As we have to calculate the percentage of score less than 80, we will find the z-score of 80

z = (x-μ) / σ

= (80-75) / 5

=5/5

=1

The z-score table value for 1 is 0.8413.

For converting this value into percentage, the value will be multiplied by 100.

So,

Percentage of students whose score is less than 80 = 0.8413*100

=84.13%

Rounding off gives us : 84%

So option B is the correct answer ...