According to records in a large hospital, the birth weights of newborns have a s

Question

According to records in a large hospital, the birth weights of newborns have a symmetric and bell-shaped relative frequency distribution with mean 6.8 pounds and standard deviation 0.5

1- Approximately what proportion of babies are born with wieght under 6.3 pounds?                           [ Select ]                       ["13.5%", "16%", "68%", "95%", "2.5%"]      

2- If a baby is born with a birth weight which has a z-score of 3, which of the following statements best describes the baby's birth weight?

Explanation / Answer

Sol:

mean=6.8

sd=0.5

P(X<6.3)

P(Z<6.3-6.8/0.5)

P(Z<-1)

=1-P(Z<1)

=1-0.8413

=0.1587

=0.1587*100

=15.87%

=16%

ANSWER:16%

Solution2:

Z score =3

Z=x-mean/sd

X-6.8/0.5=3

X=3*0.5+6.8

X= 8.3

baby's birth weight=8.3 POUNDS

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