Question

A study studied the birth weights of 1,214 babies born in the United States. The mean weight was 3234 grams with a standard deviation of 871 grams. Assume that birth weight data are approximately bell-shaped. Estimate the number of newborns who weighed between 1492 grams and 4976 grams.
Write only a number as your answer. Round your answer to the nearest whole number.

Answer 1

Solution :

Given that,

mean = = 3234

standard deviation = = 871

N =1,214

P (1492 < x < 4976 )

P ( 1492- 3234 / 871) < ( x -  / ) < ( 4976 - 3234 / 871)

P ( -1742 / 871 < z < 1742 / 871 )

P (-2 < z < 2 )

P ( z < 2 ) - P ( z < -2)

Using z table

= 0.9772 - 0.0228

= 0.9544

Probability = 0.9544

N =1214 * 0.9544 =1158.64