Question

The College Board reported the following mean scores for the three parts of the SAT:

Critical Reading	502
Mathematics	515
Writing	494

Assume that the population standard deviation on each part of the test is σ = 100.

If required, round your answers to two decimal places.

(a)	For a random sample of 30 test takers, what is the standard deviation of x for scores on the Critical Reading part of the test?
(b)	For a random sample of 60 test takers, what is the standard deviation of x for scores on the Mathematics part of the test?
(c)	For a random sample of 90 test takers, what is the standard deviation of x for scores on the Writing part of the test?

Answer 1

Solution :

a) Given that,

mean = = 502

standard deviation = = 100

n = 30

= = 502

= / n = 100 / 30 = 18.26

b) Given that,

mean = = 515

standard deviation = = 100

n = 60

=   = 515

= / n = 100 / 60 = 12.91

c) Given that,

mean = = 494

standard deviation = = 100

n = 90

=   = 494

= / n = 100 / 90 = 10.54