7.1

31.

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

Interpretation 1. The proportion of cell phone plans in the US that charge less that $44 per month is 0.1587 or 15.87%

Interpretation 2. The probability that a randomly selected cell phone plan in the US will charge less than $44 per month is 0.1587

32.

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

Interpretation 1. The proportion of refrigerators that last more than 17 years is 0.1151 or 11.51%

Interpretation 2. The probability that a randomly selected refrigerator will last more than 17 years is 0.1151

33.

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

Interpretation 1. The proportion of full term babies that weigh more than 4410 grams is 0.0228 or 2.28%

Interpretation 2. The probability that a randomly selected full term baby will weigh more than 4410 grams is 0.0228

34.

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

Interpretation 1. 0.0496 or 4.96% of 10-year-old males are less than 46.5 inches tall

Interpretation 2. The probability that a randomly selected 10-year-old male is less than 46.5 inches tall is 0.0496

35.

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

Interpretation 2. The probability that a randomly selected human pregnancy lasts longer than 280 days is 0.1908

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

Interpretation 2. The probability that a randomly selected human pregnancy will last between 230 and 260 days is 0.3416

36.

Interpretation 1. The proportion of gas tank fill ups that yield more than 26 miles per gallon is 0.3309 or 33.09%

Interpretation 2. The probability that a randomly selected fill up with yield more than 26 miles per gallon is 0.3309

Interpretation 1. The proportion of gas tank fill ups that yield between 18 and 21 miles per gallon is 0.1107 or 11.07%

Interpretation 2. The probability that a randomly selected full up will yield between 18 and 21 miles per gallon is 0.1107

7.2

5.

  1. 0.0071
  2. 0.3336
  3. 0.9115
  4. 0.9998

7.

  1. 1-0.0013= 0.9987
  2. 1-0.0559= 0.9441
  3. 1-0.9625= 0.0375
  4. 1-0.9991= 0.0009

9.

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

11.

  1. 0.0228+(1-0.9772)= 0.0456
  2. 0.0594+(1-0.9948)= 0.0646
  3. 0.4052+(1-0.8849)= 0.5203

13. -1.28

15. 0.67

17. z1= -2.575; z2= 2.575

33. 40.62

35. 65.16

37.

  1. 0.1587
  2. 0.1587
  3. 0.5-0.0228= 0.4772
  4. yes, because the probability of an egg hatching in less than 18 days is 0.0013, which is very low probability of happening

39.

  1. 0.8790-0.0132= 0.8658
  2. 0.0132
  3. 1-0.2981= 0.7019
  4. 0.1230
  5. probability=0.9649; 96th percentile
  6. probability=0.0359; 4th percentile

41.

  1. 1-0.5987= 0.4013
  2. 0.1587
  3. 0.8106-0.0516= 0.7590
  4. 1-0.8106= 0.1894
  5. 0.0951
  6. probability= 0.0043 so yes very preterm babies are unusual

43.

  1. 0.0764
  2. 0.0162+(1-0.9838)= 0.0324
  3. 5000x0.0324= 162 rods
  4. 0.9236-0.0764= 0.8472; 84.72% of 10,000= 8472 rods made, so 1528 more rods needed; 1528/0.8472= 1803.6; so company should make 11,804 rods to complete the order

45.

  1. 0.3228
  2. 0.4286
  3. this means that the likelihood of the team to win or lose is equal relative to the spread; yes because a mean of zero means the spreads are accurate

47.

  1. 20.05= 20 days is 17th percentile
  2. the middle 95% of fertilized eggs hatch between 19 and 23 days

56. ACT = scored in 83 percentile; SAT = scored in 85th percentile; so, scored better on SAT