7.1

31.

shadenorm(mu = 62, sig = 18, below = 44, col = "blue", dens = 200)

Interpretation 1. Type answer here. 15.87% of the cell phone plans in the United States are less than 44 dlooars per month. Interpretation 2. Type answer here. the probability is 0.1587 that a randomly selected cell phone plan in the United States is less than 44 dollars per month. 32.

shadenorm(mu = 14, sig = 2.5, above = 17, col = "blue", dens = 200)

Interpretation 1. Type answer here. 11.51% of the lives of refrigerators are more than 17 years. Interpretation 2. Type answer here. the probability is 0.1151 that a randomly selected refrigerator has a live of more than 17 years.

33.

shadenorm(mu = 3400, sig = 505, above = 4410, col = "blue", dens=200)

Interpretation 1. Type answer here. 2.28% of all full-term babies have a birth weight of at least 4410 grams. Interpretation 2.Type answer here. the probability is 0.0028 that the birth weight of a randomly chosen full-term baby is at least 4410 grams. 34.

shadenorm(mu = 55.9, sig = 5.7, below = 46.5, col = "blue", dens=200)

Interpretation 1. Type answer here. 4.96% of 10-year-males are shorter than 46.5 inches. Interpretation 2. Type answer here. the probability is 0.00496 that a randomly selected 10-year-old male is shorter than 46.5 inches.

35.

Interpretation 1. Type answer here. the proportion of human pregnancies that last more than 280 days is 19.08% Interpretation 2. Type answer here. the probability is 0.1908 that a randomly selected human pregancy lasts more than 280 days. (b)

Interpretation 1.Type answer here. the proportion of human pregnancies that last between 230 and 260 days is 34.16%. Interpretation 2. Type answer here. the probability is 0.3416 that a randomly selected human prenancy lasts between 230 and 260 days. 36.

Interpretation 1. Type answer here. 33.09% of the 40 times she filled up were greater 26 miles per gallon Interpretation 2. Type answer here. the probability is 0.3309 that a randomly selected time out of the 40 times she fills up is greater than 26 miles. (b)

Interpretation 1. Type answer here. 11.07% of the 40 times she fills up were in between 18 and 21 miles per gallon. Interpretation 2. Type answer here. the probability is 0.1107 that a randomly selected time out of the 40 times she fills up is in between 18 and 21 times.

7.2

5.

  1. Type answer here. the area to the left of z=-2.45 is 0.0071
  2. Type answer here. the area to the left of z=-0.43 is 0.3336
  3. Type answer here. the area to the left of z=1.35 is 0.9115

  4. Type answer here. the area to the left of z=3.49 is 0.9998 7.

  5. Type answer here. the area to the right of z=-3.01 is 1-0.0013=0.9987
  6. Type answer here. the area to the right of z=-1.59 is 1-0.0559=o.9441
  7. Type answer here. the area to the right of z=1.78 is 1-0.9625=0.0375

  8. Type answer here. the area to the right of z=3.11 is 1-0.9991=0.0009

9.

  1. Type answer here. 0.9793-0.0207=0.9586
  2. Type answer here. 0.5-0.2912=0.2088
  3. Type answer here. 0.9971-0.1492=0.8479

11.

  1. Type answer here. 0.0228+0.0228=0.0456
  2. Type answer here. 0.0594+0.0052=0.0646

  3. Type answer here. 0.4052+0.1151=0.5203 13. Type answer here. z=-1.28 15. Type answer here. z=0.67 17. Type answer here. z1=-2.575 z2=2.575 33. Type answer here. 50+(-1.34)(7)=40.62 35. Type answer here. 50+0.88(7)=56.16 37.

shadenorm(mu = 21, sig = 1.0, below = -1000, col = "blue", dens=200)

  1. Type answer here. z=-1 p=0.1587
  2. Type answer here. z=1 p=1-0.8413=0.1587
  3. Type answer here. z1=-2.11 z2=0 0.5000-0.0228=0.4772

  4. Type answer here. z=-3.00 p=0.0013 39.

  5. Type answer here. z1=-2.22 z2=1.17 p=0.8790-0.0132=0.8658
  6. Type answer here. z=-2.22 p=0.0132
  7. Type answer here. z=-0.53 p=1-0.2981=0.7019
  8. Type answer here. z=-1.16 p=0.01230
  9. Type answer here. z=1.81 p=0.9649

  10. Type answer here. z=-1.8 p=0.0359

41.

  1. Type answer here. z=0.25 p=1-0.5987=0.4013
  2. Type answer here. z=-1 p=0.1587
  3. Type answer here. z1=-1.63 z2=0.88 p=0.8106-0.0516=0.7590
  4. Type answer here. z=0.88 p=1-0.8106=0.1894
  5. Type answer here. z=-1.31 p=0.0951
  6. Type answer here. z=-2.63 p=0.0043

43.

  1. Type answer here. z=-1.43 p=0.0764
  2. Type answer here. z1=-2.14 z2=2.14 p=0.0324
  3. Type answer here. 5000(0.0324)=162
  4. Type answer here. z1=-1.43 z2=1.43 p=0.8472 x=10000/0.8472=11.80359