The lifetime of television produced by the Hishobi Company are normally distributed with a mean of 75 months and a standard deviation of 8 months. If the manufacture wants to have to replace only 1% of its televisions, what should its warranty be?

Question

The lifetime of television produced by the Hishobi Company are normally distributed with a mean of 75 months and a standard deviation of 8 months.  If the manufacture wants to have to replace only 1% of its televisions, what should its warranty be?

PsyDAG · Answer

Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion and get its Z score. Insert values into equation above and solve for the score.