Suppose that the mean and standard deviation of the weight o

Suppose that the mean and standard deviation of the \"weight of newborn infant\" distribution are = 3360 grams and = 490 grams. Select a random sample of 49 infants from the population. Find P( X > 3500).

a) .4772 b) .0228 c) .3859 d) .1141

Solution

Mean ( u ) =3360
Standard Deviation ( sd )=490
Number ( n ) = 49
Normal Distribution = Z= X- u / (sd/Sqrt(n) ~ N(0,1)                  
P(X > 3500) = (3500-3360)/490/ Sqrt ( 49 )
= 140/70= 2
= P ( Z >2) From Standard Normal Table
= 0.0228