HW6_skeleton

7.2

• 1. type answer here. Standard normal distribution
• 2. type answer here. Z(alpha)
• 3. type answer here. 0.3085
• 4. type answer here. 0.4207
• 1. type answers here. 0.0071
  2. type answers here. 0.3336
  3. type answers here. 0.9115
  4. type answers here. 0.9998
• 1. type answers here. 0.9987
  2. type answers here. 0.9441
  3. type answers here. 0.0375
     
  4. type answers here. 0.0009
• 15. type answer here. z=0.67
• 17. type answer here. z1=-2.575 z2=2.575
• 18. type answer here. z1=-1.88 z2=1.88
• 23. type answer here. 0.9838

shadenorm(mu=50, sig=7, above = 35,col = "blue",dens = 150)

• 24. type answer here. 0.0162

shadenorm(mu=50, sig=7, above = 65,col = "blue",dens = 150)

• 25. type answer here. 0.2389

shadenorm(mu=50, sig=7, below = 45,col = "blue",dens = 150)

• 1. type answers here. 0.8658
  2. type answers here. 0.0132
  3. type answers here. 0.7019 of the bags have more than 1200 chocolate chips
  4. type answers here. 0.1230 of the bags have fewer than 1125 chocolate chips
  5. type answers here. A bag that contains 1475 chocolate chips is at the 96th percentile
  6. type answers here. A bag that contains 1050 chocolate chips is at the 4th percentile.

8.1

• 1. type answer here. sample distribution
• 2. type answers here. mean, standard deviation divided by the square root of n
• 3. type answer here. standard error of the mean
• 4. type answers here. true
• 5. type answers here. false
• 6. type answers here. false
• 7. type answers here.(Need the shape, center and spread) ̅ The sampling distribution of x-bar is normal with mean =30 and standard deviation = 8 devided by the square root of 10 is equal to about 2.530.
• 8. type answers here. No the population does not need to be normally distributed for the sampling ditribution of x-bar to be approximately normally distributed because regardless of the shape of the underlying population, the sampling distribution of x-bar becomes approximately normal as the sample size, n, increases. The sampling distribution of x-bar is normal with a mean of = 50 and standard deviation = 8 divided by the square root of 40 is equal to about 1.265.
• 9. type answers here. mean = 80, standard deviation = 2
• 10. type answers here. mean x-bar= 64, standard deviation x-bar= 18/square root of 36 which is equal to 3.
• 1. type answers here.(Need the shape, center and spread) mean is approximately normal with mean x-bar = 80 and standard deviation x-bar = 20
  2. type answers here. 0.0668. If we take 100 simple random samples of size n = 49 from a population with mean = 80 and standard deviation = 14, then about 7 of the samples will result in a mean that is greater than 83.
  3. type answers here. 0.0179. If we take 100 simple random samples of size n = 49 from a population with a mean = 80 and standard deviation = 14, then about 2 of the samples will result in a mean that is less than or equal to 75.8.
  4. type answers here. =0.7969. If we take 100 simple random samples of size n = 49 from a population with mean = 80 and standard deviation = 14, then about 80 of the samples will result in a mean that is between 78.3 and 85.1.
• 1. type answers here. =0.3520. If we randomly select 100 human pregnancies, then about 35 of the pregnancies will last less than 260 days.
  2. type answers here. The sampling distribution of x-bar is normal with mean (center) = 266 and standard deviation (spread) = 16/square root of 20 equally to about 3.578.
  3. type answers here. =0.0465. If we take 100 simple random samples of size n = 20 human pregnancies, then about 5 of the samples will result in a mean gestation period of 260 days or less.
  4. type answers here. =0.0040. If we take 1000 simple random samples of size n = 50 human pregnancies, then about 4 of the samples will result in a mean gestation period of 260 days or less.
  5. type answers here. This result would be unusual. The sample most likely came from a population that had a mean gestation period that is less than 266 days.
  6. type answers here. =0.9844. If we take 100 simple random samples of size n = 15 human pregnancies, then about 98 of the samples will result in a mean gestation period between 256 and 276 days, inclusive.