6. Among a sample of new born babies, the average birthweight is 3.4 kg, with a standard deviation of 0.55 kg. A histogram of the birthweights closely follows the normal curve. (a) Approximately 95% of babies in the sample have a birthweight between kg and kg. (b) A baby's birthweight is strongly associated with mortality risk during the first year and, to a lesser degree, with developmental problems in childhood and the risk of various diseases in adulthood. The World Health Organization denes a low weight baby as one whose birthweight is less than 2.5 kg. Use the normal approximation to determine the percentage of low weight babies in the sample. (cl What is the interquartile range of birthweights in the sample? [Hint: First you need to find the first quartile (25th percentile) and third quartile {75th percentile) of the distribution of weights. To do this, recall from #2 what the 25"h and 75'\" percentiles are for the normal curve. This gives you the values for the weights but expressed in standard units. What are the corresponding birthweights, in the original units? Now, how does the IQR relate to these? Ask your GSI to help you draw a picture if you get stuck on this one!]