Question

The grades of an exam whose mean is 82 and whose standard deviation is 14 are normally distributed. Anyone who scores below 55 will be retested. What percentage does this represent

Answer 1

Answer:

This represents 2.6803%

Step-by-step explanation:

We start by calculating the z-score

Mathematically;

z-score = (x - mean)/SD

here our x is 55

mean = 82

SD = 14

z-score = (55-82)/14

z-score = -1.93

So the probability that a test taker will be retested will be;

P( x < -1.93)

We use the standard normal distribution table for this

P( x < -1.93) = 0.026803

If we convert this to percentage, we have 2.6803%