SOLUTION: A hundred squash balls are tested from the height of the bounce. A ball is fast if it rises above 32 inches. The average height of the bounce was 30inches and the standard deviatio

Question 726053: A hundred squash balls are tested from the height of the bounce. A ball is fast if it rises above 32 inches. The average height of the bounce was 30inches and the standard deviation was 3/4 inches. What is the chance of getting a fast standard ball.
Answer by Theo(13342) (Show Source): You can put this solution on YOUR website!
the mean is 30 inches.

the standard deviation is 3/4 inch.

to find p(x > 32) you need to calculate the z-score to get:

z = (32 - 30) / (3/4) which is equal to 8/3.

that's a z-score of 2.67 rounding to two decimal places.

the formula to find the z-score is:

z-score = (value - mean) / (standard deviation)

look up in the z-score tables for a z-score of 2.67 and you will find that the probability of the z-score being less than 2.67 is equal to .9962.

The probability of the z-score being greater than 2.67 is equal to 1 - .9962 which is equal to .0038.

the z-score table that i used is shown below:

http://lilt.ilstu.edu/dasacke/eco148/ztable.htm
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