Question

In psychology, there is a particular Mental Development Index (MDI) used in the study of infants. The scores on the MDI have approximately a normal distribution with a mean of 100 and standard deviation of 16. We are going to randomly select 64 children and average their MDI scores. What is the probability that the average is greater than 102?

Answer 1

Answer:

0.1587

Step-by-step explanation:

Here, mean=μ=100 and standard deviation=σ=16.

We have to find  P(average MDI scores of 64 children > 102)=P(xbar>102).

n=64

μxbar=μ=100

σxbar=σ/√n=16/√64=16/8=2

P(xbar>102)=P((xbar-μxbar)/σxbar>(102-100)/2)

P(xbar>102)=P(z>1)

P(xbar>102)=P(0<z<∞)-P(0<z<1)

P(xbar>102)=0.5-0.3413

P(xbar>102)=0.1587

Thus, the probability that the average is greater than 102 is 15.87%