Question

Babies born weighing 2500 grams (5.5 pounds) or less called low birth weight babies, and this condition sometimes indicates health problems for the infants. The mean birth weight is 3462 grams (7.6 pounds). The mean birth weight for babies born one month early is 2622 grams, Suppose the standard devaition is 500 grams

a) Find the standardized z score relative to all U.S births for a baby weighing 2500 grams

b) Find the standardized z score for a birth weight of 2500 grams, for a child born one month early using 2622 as the mean.

c) For which group is a birth weight of 2500 grams more common? Explain what that implies.

Answer 1

a) Z score for X = 2500

b) for X = 2500 using mean =2622

c) If the distribution is symmetric and normal, then any weight near the mean is considered as more common.

A birth weight of 2500g for a child born one month early is more common because the weight is 0.244 standard deviation below the mean and it is more closer to the mean than the z score 1.924.