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The Museum of Science in Boston has an exhibit in which metal balls drop down a chute, bounce around, and wind up in one of 21 bins. After 1000 balls have dropped, the heights within the bins clearly follow a bell-shaped curve. If the standard deviation is 3 bins, approximately how many balls are in bins 1 through 7?

A) 100
B) 160
C) 50
C) 330

Answer :

Dontthankmebrainme
if you have 21 bins then the 'middle bin' is bin 11 (starting at 1) So the 'mean' of this distribution is 11. The SD is 3 so using the above calculator (or your own tables ) you get that the probability of a ball being in bin 7 or less is .091

A is you answer
A.100 so make sure you put your answer

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