Question

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?

Answer 1

This is example of Normal distribution. The central bin is: (21+1)/2=11
If the standard deviation is 3, we have 11-3=8 For bins:1-7 (graph of Normal distribution, or bell-shaped curve) we have 15.87% of all of the balls.
0.1587*1000=158.7.
Answer: We have approximately 159 balls in bins 1 through 7.