Medal
a compact disc is designed to last an average of 4 years with a standard deviation of 0.9 years. what is the probability that a cd will last less than 3 years?
1.11%
13.35%
86.65%
100%

This question is of one using standard deviation to answer a question. This practice is widely used in statistics to make a general or close answer for a statistics problem that is usually convoluted. Here we take the first leg from the central point to the edge of the point of 1, which is about 34% away. Anything under is around 16% so the answer is now 13.35%.