7.1

31.

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

Interpretation 1. 15.87% have plans that charge less than $44 per month

Interpretation 2. The probability that someone will have a plan that charges less than $44 per month is .1587

32.

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

Interpretation 1. 11.51% of refrigerators last more than 17 years

Interpretation 2. The probability that a refrigerator will last more than 17 years is .1151

33.

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

Interpretation 1. 2.28% of full-term babies have birth weights that are more than 4410 grams.

Interpretation 2. The probability that full term babies have birth weights that are more than 4410 grams is .0228

34.

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

Interpretation 1. 4.96% of 10 year old males are less than 46.5 inches tall.

Interpretation 2. The probability that a 10 year old boy is under 46.5 inches tall is .0496

35.

Interpretation 1. 19.08% of human pregnancies last more than 280 days.

Interpretation 2. The probability that a human pregnancy will last more than 280 days is 0.1908.

Interpretation 1. 34.16% of pregnancies last between 230 and 260 days.

Interpretation 2. The probability that a human pregnancy lasts between 230 and 260 days is 0.3416.

36.

Interpretation 1. 33.09% of the time the gas tank will last more than 26 miles.

Interpretation 2. The probability that the gas tank will last more than 26 miles is 0.3309.

Interpretation 1. 11.07% of the time the gas tank will last between 18 and 21 miles.

Interpretation 2. The probability that the gas tank will last between 18 and 21 miles is 0.1107.

7.2

5.

  1. 0.0071
  2. 0.3336
  3. 0.9915
  4. 0.9998

7.

  1. 0.9987
  2. 0.9441
  3. 0.0375
  4. 0.0009

9.

  1. 0.9586
  2. 0.2088
  3. 0.8479

11.

  1. 0.0456
  2. 0.0646
  3. 0.5203

13. -1.28

15. 0.67

17. z1= -2.575 and z2= 2.575

33. x= 40.62

35. 56.16

37.

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

  1. The probability that a randomly selected egg will hatch in less than 20 days is 0.1587.
  2. The probability that a randomly selected egg takes over 22 days to hatch is 0.1587.
  3. The probability that a randomly selected egg hatches between 19 and 21 days is 0.4772.
  4. Yes.

39.

  1. The probability that a randomly selected bag of Chips Ahoy contains between 1000 and 14000 chocolate chips is 0.8658.
  2. The probability that a randomly selected bag of cookies contains fewer than 1000 chocolate chips is 0.0132.
  3. 0.7019 of the 18oz bag contains more than 12000 chocolate chips
  4. 0.1230 of the 18oz bag contains 1475 chocolate chips
  5. the 96th percentile
  6. the 4th percentile

41.

  1. 0.4013 of pregnancies last more than 270 days
  2. 0.1587 of pregnancies last less than 250 days
  3. 0.7590 of pregnancies last between 240 and 280 days
  4. The probability that a randomly selected pregnancy lasts more than 280 days is 0.1894
  5. 0.0951
  6. Yes.

43.

  1. .0764 of the rods have a length less than 24.9cm.
  2. .0324 of the rods will be discarded.
  3. 162 of the 5000 rods are expected to be discarded.

45.

  1. Yes, it does imply that the soreads are accurate for games in which a team is favored by 12 or fewer points
  2. 0.3228
  3. 0.4286

47.

  1. 20 days.
  2. 19-23 days.

56. I scored better on the SAT, because, when drawing each curve, my SAT score was more than one standard deviation above the mean, while my ACT score was less than one standard deviation above the mean.