Desperately need exact answer

Question

Cans of regular soda have volumes with a mean of 12.58 oz and a standard deviation of 0.12 oz. Is it unusual for a can to contain 12.88 oz of soda?

 

What is the Minimum? "usual" valu= in  oz

Answer 1

if the mean is 12.58 oz the likelihood of getting 12.88 or 0.3 oz overfill is 0.3/0.12 = 2.5 standard deviation above the mean.

 

This likelihood can be found by looking up the one tail probability of 2.5σ.

 

0.621% - thus very unusual or about 6 out 1000 cans

 

The minimum "usual" value depends on who is asking but  is typically considered mean -1σ, or in this case 12.76 oz