for that the distribution of net typing rate in words per minute (wpm) experienc
ID: 3205181 • Letter: F
Question
for that the distribution of net typing rate in words per minute (wpm) experienced typists can be approximated by a normal curve with mean 64 wpm and standard deviation 20 wpm. (Round all answers to four decimal places.) (a) What is the probability that a randomly selected typist's net rate is at most 64 wpm? what is the probability that a randomly selected typist's net rate is less than 64 wpm? (b) What is the probability that a randomly selected typist's net rate is between 24 and 104 wpm? 0.9545 (c) suppose that two typists are independently selected. What is the probability that both their typing rates exceed 104 wpm? 9552 (d) suppose that special training is to be made available to the slowest 20% of the typists. What typing speeds would qualify individuals for this training? (Round the answer to one decimal place.) or less words per minuteExplanation / Answer
ans=
(a)
Here,
Mean = 62
Standard Deviation = 20
Z = ((X – Mean) / SD)
= ((64 – 64) / 20)
=0
So the probability that a randomly selected typist's net rate is at most 62 wpm is
P (Z < 0)
=0.5
B)Here,
Mean = 64
Standard Deviation = 20
Z1 = ((X – Mean) / SD)
= ((24 – 64) / 20)
=-2
Z2 = ((X – Mean) / SD)
= ((104 – 64) / 20)
=2
So the probability that a randomly selected typist's net rate is between 22 and 102 wpm is
P (-2 < Z1 < 2)
= 0.954499736
C) z-value for a speed of 104 wpm = (104 - 64) / 20 = 2.00
Probability that a typist exceeds this = 0.0228 (from table).
Probability that both typists exceed this level = 0.0228² = 0.0338
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