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Assignment #1: Due Monday, September 28

All assignments should be handed in on letter-size (8.5” by 11”) paper and stapled to minimize misplaced assignments during grading. Legibly state your name on the upper right corner of the first page. You should show your work for all problems. If you use computer software such as Excel data analysis, attach all relevant computer outputs.

1.110 (p. 62), 1.112 (p. 62), 1.114 (p. 63), 1.132 (p. 67), 4.110 (p. 275), 4.120 (p. 276), 4.122 (p. 276)

1.110 Length of pregnancies. Some health insurance companies treat pregnancy as a “preexisting condition” when it comes to paying for maternity expenses for a new policyholder. Sometimes the exact date of conception is unknown, so the insurance company must count back from the expected due date to judge whether or not conception occurred before or after the new policy began. The length of human pregnancies from conception to birth varies according to a distribution that is approximately Normal with mean 266 days and standard deviation 16 days. Use the 68–95–99.7 rule to answer the following questions.

(a) Between what values do the lengths of the middle 95% of all pregnancies fall?

(b) How short are the shortest 2.5% of all pregnancies?

(c) How likely is it that a woman with an expected due date 218 days after her policy began conceived the child after her policy began?

1.112 Use Table A. Use Table A to find the value of z for each of the situations below. In each case, sketch a standard Normal curve and shade the area representing the region.

(a) Ten percent of the values of a standard Normal distribution are greater than z.

(b) Ten percent of the values of a standard Normal distribution are greater than or equal to z.

(c) Ten percent of the values of a standard Normal distribution are less than z.

(d) Fifty percent of the values of a standard Normal distribution are less than z.

1.114 Length of pregnancies. The length of human pregnancies from conception...