The birth weights for twins are normally distributed with a mean of 2353 grams and a standard deviation of 647 grams. use​ z-sco

Designate X as the birth weight for twins, which follows a normal distribution with an average μ = 2353 and a standard deviation σ = 647

Any z score that is below -2 or exceeds 2 is deemed unusual. Conversely, if the z score is within the range of -2 to 2, it is classified as usual.

To identify unusual birth weights, we will calculate the z scores for each x value. An x value that produces a z score of less than -2 or more than 2 is noted as unusual.

a. x=1200

z =

z =

z = -1.78

The z score falls between -2 and 2, therefore x=1200 is considered usual.

b. 2353

z =

z = 0

Since z=0 is within the bounds of -2 and 2, x=2353 is classified as usual.

c. 2000

z =

z = -0.5456

The z score of -0.5456 is between -2 and 2, which makes x=2000 usual.

d. 3647

z =

z = 2

A z score of 2 is the upper threshold for unusual values, thus x=3647 is regarded as usual.