SOLUTION: The scores on the psychomotor development index (PDI), a scale of infant development, are approximately normal with mean mu=100 and standard deviation sigma=18. What is the probab

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Question 437313: The scores on the psychomotor development index (PDI), a scale of infant development, are approximately normal with mean mu=100 and standard deviation sigma=18. What is the probability that the average score of 25 infants exceeds 108?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi

*Note: z+=blue+%28x+-+mu%29%2Fblue%28sigma%2Fsqrt%28n%29%29

mean mu=100 and standard deviation sigma=18.

 P(x>108 for sample of 25)   z = 8/(18/5)= 2.2222

P(z > 2.222) = .0131     | 1 - NORMSDIST(2.2222) = 1 -.9869