Babies born weighing 2500 grams about 55 pounds or less are

Babies born weighing 2500 grams (about 5.5 pounds) or less are called low-birth-weight babies, and this condition sometimes indicates health problems for the infant. The mean birth weight for children born in a certain country is about 3476 grams (about 7.6 pounds). The mean birth weight for babies born one month early is 2695 grams. Suppose both standard deviations are 450 grams. Also assume that the distribution of birth weights is roughly unimodal and symmetric. Complete parts a through e below. Find the standardized score (z-score), relative to all births in the country, for a baby with a birth weight of 2500 grams. Find the standardized score for a birth weight of 2500 grams for a child born one month early, using 2695 as the mean. For which group is a birth weight of 2500 grams more common? Explain what that implies. Unusual z-scores are far from 0. Choose the correct answer below. A birth weight of 2500 grams is more common for all births in the country. This makes sense because the group of all births in the country is much larger than the group of births that are one month early. Therefore, more babies will have low birth weights among all births in the country A birth weight of 2500 grams is more common for babies born one month early. This makes sense because babies gain weight during gestation, and babies born one month early had less time to gain weight. A birth weight of 2500 is equally as common to both groups. It cannot be determined to which group a birth weight of 2500 grams is more common.

Solution

a.Z=(given weight-mean weight)/standard deviation

=(2500-3453)/470=-2.03.

b.Z=(given weight-mean weight)/standard deviation

=(2500-2684)/470=-0.39.

c.Less the magnitude of Z value more is the frequency.Thus from above calculations it implies that the correct answer is option B.The explanation is also correct.