i want knew how they got 32 % as the answer

Question

Objects that are manufactured to certain specifications tend to vary slightly from their specified measurements. In answering the following, assume the measurements are normally distributed.
 
A brand of crockpots has a mean high temperature of 260º F and a standard deviation of 3º F. If acrockpot′
s
highest temperature is below 257º F or above 263º F, it is considered defective. What percentage of these pots can be expected to be defective? 32%

Answer 1

The stated conditions such that an OK crockpot has temperature data within ±one standard deviation of the mean.

It is well known that this constitutes 68% (rounded to an integer), so therefore the rest, 32%, would be defective under the stated definition.