I need help with question number 2 please! The National Center for Health Statis
ID: 3205063 • Letter: I
Question
I need help with question number 2 please! The National Center for Health Statistics (NCHS) keeps records of many health-related aspects of people, including the birth weights of all babies born in the United States. The birth weight of a baby is related to its gestation period (the time between conception and birth). For a given gestation period, the birth weights can be approximated by a normal distribution. The means and standard deviations of the birth weights for various gestation periods are shown in the table below. One of the many goals of the NCHS is to reduce the percentage of babies born with low birth weights. The figure below shows the percents of preterm births and low birth weights from 1996 to 2010. The distributions of birth weights for three gestation periods are shown. Match the curses with the gestation periods. Explain your reasoning. What percent of the babies born within each gestation period have a low birth weight (under 55 pounds)? Under 28 weeks 32 to 33 weeks 39 weeks 42 weeks and over Describe the weights of the top 10% of the babies born within each gestation period. Under 28 weeks 34 to 36 weeks 40 to41 weeks 42 weeks and over For each gestation period, what is the probability that a baby will weigh between 6 and 9 pounds at birth? Under 28 weeks 28 to 31 weeks 34 to 36 weeks 39 weeks A birth weight of less than 3.25 pounds is classified by the NCHS as a "very low birth weight." What is the probability that a baby has a very low birth weight for each gestation period ? Under 28 weeks 28 to 31 weeks 32 to 33 weeks 39 weeks
Explanation / Answer
This question can be answered from the information given in the table. If the mean +/- 3 SD is less than 5.5, then all the babies born in that gestation period will have weights less than 5.5
For babies under 28 weeks:
mean = 1.90 + 3 (1.23) = 5.5
Thus, almost all babies born before 28 weeks will have weights below 5.5 pounds
Hope this helps.
P.S : This can be checked with other options and will result into much more than 5.5 pounds every time.