Question

In a biology course, recent test grades follow a normal distribution with a mean of 70 and a standard deviation of 7. If a student scored at the 70th percentile on a recent test, then what is the actual score on his test paper??

Answer 1

Solution :

mean = = 70

standard deviation = = 7

Using standard normal table,

P(Z < z) = 70% = 0.70

P(Z < 0.52) = 0.70

z = 0.52

Using z-score formula,

x = z * +

x = 0.52 * 7 + 70 = 73.64

The actual score on his test paper = 73.64