A random sample of 25 observations is to be drawn from a population with the mean of 40 and a standard deviation of 25. The probability that the mean of the sample will exceed 45 is:
a.Not possible to compute
b. 0.4772
c. 0.4207
d. 0.0228
Solution: Here, the given information are
n=25, =40, =25
The probability that the mean of the sample will exceed 45 is:
P(>45) =1-P(<45) ------------------ P(x>a)=1-P(x<a)
=1- --------------------(using central limit theorem for mean)
=1-P(z<1)
= 1-0.8413-----------(from z table)
=0.1587
The correct option is a) Not possible to compute based on the information provided.
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