2. Suppose that the distribution of net typing rate in words per minute (wpm) for experienced...

  

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2. Suppose that the distribution of net typing rate in words per minute (wpm) for experienced typists is normal with mean 60 wpm and standard deviation 15 wpm. Find the probability that the randomly selected typist's net rate is (a) (4 points) at least 60 wpm. (b) (4 points) at most 120 wpm. (c) (4 points) between 60 and 120 wpm. Answer: Answer: Answer: (d) (4 points) Suppose that special training is to be made available to the fastest 20% of the typists. What typing speeds would qualify individuals for this training? Answer: (e) If 16 typists are randomly selected and the sample mean of their typing speed (in wpm) are calculated. Let X denote the sample mean of the typing speed. i. (2 points) What is the mean of X? ii. (3 points) What is the variance of X? Answer: Reason: Answer: iii. (3 points) Is the distribution of average typing speed exactly or approximately nor- mal? (circle one) Exactly/ Approximately iv. (4 points) What is the probability that the average typing speed is at least 60 wpm? 2. Suppose that the distribution of net typing rate in words per minute (wpm) for experienced typists is normal with mean 60 wpm and standard deviation 15 wpm. Find the probability that the randomly selected typist's net rate is (a) (4 points) at least 60 wpm. (b) (4 points) at most 120 wpm. (c) (4 points) between 60 and 120 wpm. Answer: Answer: Answer: (d) (4 points) Suppose that special training is to be made available to the fastest 20% of the typists. What typing speeds would qualify individuals for this training? Answer: (e) If 16 typists are randomly selected and the sample mean of their typing speed (in wpm) are calculated. Let X denote the sample mean of the typing speed. i. (2 points) What is the mean of X? ii. (3 points) What is the variance of X? Answer: Reason: Answer: iii. (3 points) Is the distribution of average typing speed exactly or approximately nor- mal? (circle one) Exactly/ Approximately iv. (4 points) What is the probability that the average typing speed is at least 60 wpm?