Question

Suppose that the mean and standard deviation of the scores on a statistics exam are 78 and 6.11, respectively, and are approximately normally distributed. Calculate the proportion of scores above 74.

Question 10 options:

	1) 0.1920
	2) 0.8080
	3) 0.7437
	4) We do not have enough information to calculate the value.
	5) 0.2563

Answer 1

Solution :

Given that ,

mean = = 78

standard deviation = = 6.11

P(x > 74) = 1 - p( x< 74)

=1- p P[(x - ) / < (74 - 78) / 6.11]

=1- P(z < -0.6547)

Using z table,

= 1 - 0.2563

= 0.7437

correct option is = 3