7.1

31.

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

Interpretation 1. 15.87% plans are less than 44$

Interpretation 2. The probability of a US cell phone plan being less than 44$ is .1587

32.

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

Interpretation 1. 11.51% of refridgerators last longer than 17 years.

Interpretation 2. The probability of a refridgerator lasting longer 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 weigh more than 4410 grams.

Interpretation 2. The probability of a full-term baby weighing 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 ten-year-old males are shorter than 46.5 inches.

Interpretation 2. The probability of a ten-year-old male being shorter than 46.5 inches is .0496

35.

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

Interpretation 2. The probability of a random pregnancy lasting longer than 280 days is .1908

Interpretation 1. the probability of a randomly selected human pregnancy lasting between 230 and 260 days is 34.16%

Interpretation 2. the proportion of human pregancies lasting between 230 and 260 days is .3416

36.

Interpretation 1. the proportion of 26 mpg or more in Elena’s camry is .3309

Interpretation 2. The probability of Elena getting more than 26 mpg after a fill up is 33.09%

Interpretation 1. .1107 is the proportion of times Elena’s car should get between 18 and 21 mpg after a fill up.

Interpretation 2. The probability of Elena getting between 18 and 21 mpg after a fill up is 11.07%

7.2

5.

  1. .0071
  2. .3336
  3. .9115
  4. .9998

7.

  1. .9987
  2. .9441
  3. .1788
  4. .0999

9.

  1. .9586
  2. .2088
  3. .8479

11.

  1. .0456
  2. .2088
  3. .8479

13. z = -1.28

15. z = .67

17. z= 2.575 z= -2.575

33. 40.62

35. 56.16

37.

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

  1. .1587; expect 16 of 100 eggs to incubate in less than 20 days.
  2. .1587; expect 16 of 100 eggs to incubate in more than 22 days.
  3. .4772; expect 48 of 100 eggs to incubate in between 19 and 21 days.
  4. yes it is unlikely -> .0013 is the probability of an egg hatching in less than 18 days. (.13% of 100 eggs, about 1.3 eggs in one thousand expected to hatch)

39.

  1. .8658
  2. .0132
  3. 70.19% (.7019) of the bags have more than 1200 chocolate chips
  4. 12.30% (.1230) of the bags have less than 1125 chips
  5. 1475 chips = 96th percentile
  6. 1050 chips = 4th percentile

41.

  1. 40.13% of pregnancies last more than 270 days
  2. 15.87% of pregnancies last less than 250 days
  3. 75.90% of pregnancies last b/w 240 and 280 days
  4. .1894
  5. .0951
  6. yes: preterm births have .43% chance aka less than one in one in one hundred (about 4 per thousand)

43.

  1. 07.64% are shorter than 24.9cm
  2. 03.24% of rods will be thrown out.
  3. plan to discard 162 of the 5000 rods
  4. manufacture 11804 to meet goal

45.

  1. each team is equally likely to win or lose yes a mean of 0 means accurate spread
  2. 32.38%
  3. 42.86%

47.

  1. 20 days = 17th percentile
  2. mid 95% = 19 to 23 days

56. scoring the 26 on the ACT is a better accomplishment because the probability of scoring that high is lower than the probability of scoring a 1240 which is a higher percentage.