Question

A set of chemistry exam scores are normally distributed with a mean of 70 points and a standard deviation
of 5 points.
What proportion of exam scores are between 68 and 73 points?
You may round your answer to four decimal places.
please help ​

Answer 1

Answer:

38.117%

Step-by-step explanation:

Firstly, what you do is to calculate the z-score of both points

Mathematically;

z-score = (x-mean)/SD

where mean = 70 and SD = 5

For 68, z-score = (68-70)/5 = -2/5 = -0.4

for 73, z-score = (73-70)/5 = 3/5 = 0.6

The probability we are to calculate ranges from

P(-0.4<z<0.6) = P(z<0.6) - P(z<-0.4)

it is at this point that we make use of z score table

= 0.38117 which is 38.117%

Answer 2

Answer:

0.3812

Step-by-step explanation:

The proportion of exam scores between 68 and 73 points is 0.3812 or 38%!