Chapter 6, Problem 14SE

Length of Pregnancy Assume that the lengths of pregnancy for humans is approximately Normally distributed, with a mean of 267 days and a standard deviation of 10 days. Use the Empirical Rule to answer the following questions. Do not use the technology or the Normal table. Begin by labeling the horizontal axis of the graph with lengths, using the given mean and standard deviation. Three of the entries are done for you.

a. Roughly what percentage of pregnancies last more than 267 days?

i. almost all

ii. 95%

iii. 68%

iv. 50%

b. Roughly what percentage of pregnancies last between 267 and 277 days?

i. 34%

ii. 17%

iii. 2.5%

iv. 50%

c. Roughly what percentage of pregnancies last less than 237 days?

i. almost all

ii. 50%

iii. 34%

iv. about 0%

d. Roughly what percentage of pregnancies last between 247 and 287 days?

i. almost all

ii. 95%

iii. 68%

iv. 50%

e. Roughly what percentage of pregnancies last longer than 287 days?

i. 34%

ii. 17%

iii. 2.5%

iv. 50%

f. Roughly what percentage of pregnancies last longer than 297 days?

i. almost all

ii. 50%

iii. 34%

iv. about 0%