SOLUTION: The mean time taken by all participants to run a road race was found to be 220 minutes with a standard deviation of 20 minutes. Using the 68 – 95 – 99.7 Rule, find the percentage

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Question 618949: The mean time taken by all participants to run a road race was found to be 220 minutes with a standard deviation of 20 minutes. Using the 68 – 95 – 99.7 Rule, find the percentage of runners who ran this race:
a. In less than 180 minutes
b. In more than 220 minutes
c. In between 160 and 280 minutes
d. In at least 240 minutes
e. In no more than 200 minutes
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

The mean time taken by all participants to run a road race was found to be 220 minutes with SD= 20min

Using the 68 – 95 – 99.7 Rule, find the percentage of runners who ran this race:

a. In less than 180 minutes (2 SD) (1-.95)/2 = 2.5%

 b. In more than 220 minutes  50%

 c. In between 160 and 280 minutes (3 SD)  99.7%

 d. In at least 240 minutes .50+%2B+.68%2F2   84%

 e. In no more than 200 minutes .50+-+.68%2F2   16%