1)The number of chocolate chips in an18-ounce bag of chocolate chip cookies is approximately normally distributed with mean 1252 and standard deviation 129 chips. (a) What is the probability that a randomly selected bag contains between 1100 and 1400 chocolatechips? (b) What is the probability that a randomly selected bag contains fewer than 1000 chocolatechips? (c) What proportion of bags contains more than 1200 chocolatechips? (d) What is the percentile rank of a bag that contains 1025 chocolatechips?

2)The lengths of a particularanimal's pregnancies are approximately normallydistributed, with mean =259 days and standard deviation =12 days. (a) What proportion of pregnancies lasts more than 268 days? (b) What proportion of pregnancies lasts between 253 and 262 days? (c) What is the probability that a randomly selected pregnancy lasts no more than 247 days? (d) A"very preterm" baby is one whose gestation period is less than 241 days. Are very preterm babiesunusual?

3)Suppose that the lifetimes of light bulbs are approximately normallydistributed, with a mean of 56 hours and a standard deviation of 3.3 hours. With thisinformation, answer the following questions. (a) What proportion of light bulbs will last more than 60 hours? (b) What proportion of light bulbs will last 53 hours orless? (c) What proportion of light bulbs will last between 58 and 61 hours? (d) What is the probability that a randomly selected light bulb lasts less than 45 hours?

4)he number of chocolate chips in a bag of chocolate chip cookies is approximately normally distributed with a mean of 1263 chips and a standard deviation of 117 chips. (a) Determine the 25th percentile for the number of chocolate chips in a bag. (b) Determine the number of chocolate chips in a bag that make up the middle 96% of bags.