Self-Check 7.1
- Page ID
- 36494
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Name:___________________________________Date:__________________Row:___________ Self-Check 7.1
- The length of time taken on the SAT for a group of students is normally distributed with a mean of 2.5 hours and a standard deviation of 0.25 hours. A sample size of n=60 is drawn randomly from the population.
- In words, 𝑋 =
- In words, 𝑋̅ =
- 𝑋̅~
- Find the probability that the sample mean is between two hours and three hours.
- Find the 80th percentile for the sample mean hours (two decimal place).
- A gondola carries skiers to the top of a mountain. It bears a plaque stating that the maximum capacity is 12 people or 2004 lb. That capacity will be exceeded if 12 people have weights with a mean of 2004/12 = 167 lb. Because men tend to weigh more than women, a worst case scenario would be if all 12 passengers were men. Men have weights that are normally distributed with a mean of 172 lb and a standard deviation of 29 lb.
- Find the probability that if an individual man is randomly selected, his weight is greater than 167 lb.
- Find the probability that 12 randomly selected men will have a mean that is greater than 167 lb.
- In a recent study reported Oct. 29, 2012 on the Flurry Blog, the mean age of tablet users is 34 years. Suppose the standard deviation is 15 years. Take a sample of size n= 100.
- What are the mean and standard deviation for the sample mean ages of tablet users?
- Find the probability that the sample mean age is more than 30 years.
- Find the 95th percentile for the sample mean age (to one decimal place).