Question

Tom's psychology test score is +1 standard deviation from the mean in a normal distribution. The test has a mean of 60 and a standard deviation of 6. Tom's percentile rank would be approximately ______________.

a. 70%

b. cannot determine from the information given

c. 84%

d. 66%

Answer 1

Given that, mean = 60 and standard deviation = 6

Tom's psychology test score is +1 standard deviation from the mean in a normal distribution.

According to Empirical rule, approximately 68% of the data fall within 1 standard deviations of the mean.

And 100 - 68 = 32% of the data fall outside the 1 standard deviations of the mean.

32/2 = 16% of the data fall below/above the 1 standard deviations of the mean.

Therefore, 16 + 68 = 84% of the data fall below +1 standard deviations from the mean.

Therefore, Tom's percentile rank would be approximately 84%.

Answer : c) 84%