statistics

The distance travelled in a week by sales staff employed by a nationwide security firm is approximately normally distributed with a mean of 200 miles and standard deviation of 48 miles.

a) less than 80 miles,
b) more than 250 miles,
c) between 100 and 300 miles.
d) A reduced mileage rate is to be introduced which is to be set such that approximately 20% of the sales staff will be affected? What is the maximum number of miles per week that a member of staff could travel before reaching the reduced mileage rate?
e) Complete this sentence:
”80% of sales staff travel between ---------------------------- and ---------------------------- miles each week”

Can someone help?

asked by Joshua
  1. a-c) Z = (score-mean)/SD

    Find table in the back of your statistics text labeled something like like "areas under normal distribution" to find the proportion/probability related to the Z scores.

    (d,e) Look up % in table to get Z score.

    posted by PsyDAG

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