7.1

31.

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

Interpretation 1. The proportion of monthly charges for cell phone plans in the US under $44 is 0.1587

Interpretation 2. The probability of a randomly selected cell phone in the US with a monthly charge under $44 is 0.1587

32.

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

Interpretation 1. The proportion of refridgerators with lives longer than 17 years is 0.1151

Interpretation 2. The probability of a randomly selected refridgerator having a life of over 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 born weighing over 4410 grams is 0.0228

Interpretation 2.The probability of a randomly selected full-term baby weighing over 4410 grams is 0.0228

34.

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

Interpretation 1. The proportion of 10-year-old males under 46.5 inches tall is 0.0496

Interpretation 2. The probability of a randomly selected 10-year-old male being under 46.5 inches tall is 0.0496

35.

Interpretation 1. The proportion of human gestation period being over 280 days is 0.1908

Interpretation 2. The probability of a randomly suggested human’s gestation period being over 280 days is 0.1908

Interpretation 1. The proportion of human gestation periods between 230 and 260 days is 0.3416

Interpretation 2. The probability of a randomly suggested human’s gestation period being between 230 and 260 days is 0.3416

36.

Interpretation 1. The proportion of Elena’s car getting over 26 miles per gallon of gas is 0.3309

Interpretation 2. The proportion of Elena’s car randomly getting over 26 miles per gallon of gas is 0.3309

Interpretation 1. The proportion of Elena’s car getting between 18 and 21 miles per gallon of gas is 0.1107

Interpretation 2. The proportion of Elena’s car randomly getting between 18 and 21 miles per gallon of gas is 0.1107

7.2

5.

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

7.

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

9.

  1. Area = 0.9586
  2. Area = 0.2088
  3. Area = 0.8479

11.

  1. Area = 0.0456
  2. Area = 0.0646
  3. Area = 0.5203

13. z = -1.28

15. z = 0.67

17. z1 = -2.575 , z2 = 2.575

33. x = 40.62 is at the 9th percentile

35. x = 56.16 is at the 81st percentile

37.

  1. P(x<20) = 0.1587
  2. P(x>22) = 0.1587
  3. P(19<x<21) = 0.4772
  4. Yes, P(x<18) = 0.0013, 1 egg in 1000 hatches in less than 18 days

39.

  1. P(1000 < X < 1400) = 0.8658
  2. P(X<1000) = 0.0132
  3. 0.7019 of the bags have over 1200 chocolate chips
  4. 0.1230 of the bags have less than 1125 chocolate chips
  5. A bag with 1475 chocolate chips is at the 96th percentile
  6. A bag with 1050 chocolate chips is at 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. P(X>280) = 0.1894
  5. P(X<245) = 0.0951
  6. Yes, 0.0043 of births are very preterm, 4 in every 1000 births are very preterm

43.

  1. 0.0764 of the rods are less than 24.9 cm long
  2. 0.0324 of the rods will be discarded
  3. The plant manager expects to discard 162 of the 5000 rods made
  4. 11804 rods

45.

  1. P(X>5) = 0.3228
  2. P(X<-2) = 0.4286
  3. It means that the favored team is equally likely to win or lose relative to the spread. Yes spreads are accurate because the mean of 0 implies accuracy.

47.

  1. 17th percentile is 20 days
  2. 19 to 23 days makes up the middle 95% of incubation time of eggs

56. You scored better on the SAT because you are in a higher percentile than with your ACT score.