Question

Use the normal distribution of SAT critical reading scores for which the mean is

510

and the standard deviation is

111

Assume the variable x is normally distributed.

a)	What percent of the SAT verbal scores are less than 625?
(b)	If 1000 SAT verbal scores are randomly​ selected, about how many would you expect to be greater than 525?

Answer 1

a) P[X<625]

  

=P[Z<1.04]

=0.8508.........................by using Z table.

Therefore, 85.08% of the SAT verbal scores are less than 625

b)

P[X>525]

=P[Z>0.14]

=1-0.5557....................by using Z table.

=0.4443

Therefore, 1000*0.4443=444.3

If 1000 SAT verbal scores are randomly​ selected, then 444 or 445  would we expect to be greater than

525