5 a. 0.0071 b. 0.3336 c. 0.9115 d. 0.9998 7 a. 0.9987 b. 0.9441 c. 0.0375 d. 0.0009 9 a. 0.9586 b. 0.2088 c. 08479 11 a. 0.0456 b.0.0646 c. 0.5203 13 z = -1.28 15 z = 0.67 17 z(1) = -2.575 z(2) = 2.575 33 x = 40.62 34 x = 12.01 35 x - 56.16 36 x = 38.49 37 a. 0.1587 b.0.1587 c. 0.4772 39 a. 0.8658 b. 0.0132 c. 0.7019 of the bags have more than 1200 chocolate chips d. 0.1230 of the bags have fewer than 1125 chocolate chips 41 a. 0.4013 of pregnancies last more than 270 days b. 0.1587 of pregnancies last fewer than 250 days c. 0.7590 of pregnancies last between 240 and 280 days d. P(X>280) = 0.1894 e. P(X is less than or equal to 245) = 0.0951 f. Yes; about 4 out of every 100 births are very preterm 43 a. 0.0764 b. 0.0324 c. 162 of the 5000 rods will be discarded d. Plant manager should manufacture 11,804 rods 45 a. 0.3228 b. 0.4286 47 a. 20 days b. 19-23 days