- 68% Frequency (or relative frequency) 95% 99.7% -30 -20 -O mean +0 +20 +30 1. Suppose the weights of newborn infants are normally distributed with a mean of 6 Ibs. and a standard deviation of 1 lb. If approximately 2,000 infants are born at Sarasota Memorial Hospital each year, determine the approximate number of infants who are expected to weigh a. Between 5 and 7 Ibs. b. Between 4 and 8 Ibs. C. 99.7% of the infants will fall in the weight range of _ Ibs. to Ibs. 2. A normal distribution has a mean of 100 and a standard deviation of 10. Determine the z-scores for the following values. a. 110 b. 115 C. 100 d. 84