Statistics homework help

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Statistics homework help. MAT 308
Test 1 Chapters 6 & 7(170 Total Points)
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Name:_______________

  1. Find the value of Z such that 0.0500 of the area under the curve lies to the right of the Z (5 points).

 

  1. Find the value of Z such that 0.2000 of the area under the curve lies to the left of the Z (5 points).

 

  1. The random variable X has a normal distribution with a mean of 100 and a standard deviation of 25(5 points each).
  2. Find probability that X is between 85 & 120
  3. Find probability that X is greater than 130
  4. Find probability that X is less than 75
  5. Find probability that X is between 95 & 105
  6. Find probability that X is less than 100

 

  1. Suppose the random variable X has a population mean of 50 and a standard deviation of 10. Calculate the mean and the standard deviation of the sample mean for each of the following sample sizes (5 points each).
  2. n=25
  3. n=40
  4. n=55
  5. n=65
  6. What happens to the size of the standard deviation of the sample mean as the sample size increases?

 

  1. A national report stated that 72% of trucks sold were extended cab. John took a random sample of 200 trucks. What is the probability that less than 116 trucks were extended cab?(10 points)

 

  1. Find the Z-score for (5 points each):
  2. Area of .9870 to its left
  3. Area of 0.035 to its right
  4. Area represents the 40th percentile
  5. Area between –Z and Z is 0.90
  6. Area to left of –Z and the right of Z totals 0.20

 

  1. Calculate the standard score (Z-Score)(5 points each).

 

  1. μ = 95 and σ = 15; x = 110

 
 

  1. μ = 110 and σ = 12.5; x = 70

 
 

  1. μ = 100 and σ = 22; x = 115

 
 

  1. With a standard normal distribution find (5 points each):

 

  1. area between -1.00 and 1.00
  2. area less than 2.45
  3. area more than -2.05
  4. area less than -.55 and more than .85

 

  1. Body temperatures of adults are normally distributed with a mean of 98.6˚ and a standard deviation of 0.45˚.What is the probability that a healthy adult will have a temperature that differs from the mean by more than 2.00˚?(10 points)

 

  1. The heights of women are normally distributed with a mean of 63.6 inches and a standard deviation 2.8 inches. With a sample size of 35 women find (5 points each):
  2. Probability that an individual woman is more than 71.5 inches tall

 

  1. Probability that the sample of women are less than 65.5 inches tall

 

  1. Probability that the sample of women are between 56.5 and 71.5 inches tall

 

  1. Probability that the sample of women are less than 64 inches or greater than 72 inches tall

 

  1. In one region, the September energy consumption levels for single-family homes are found to be normally distributed with a mean of 1150 kw and a standard deviation of 228kw. If 50 different homes are randomly selected, find the probability that their mean energy consumption level for September is greater than 1175kw (10 points).

 
 
 
 
 

Statistics homework help