A manufacturing company produces electric insulators. If the insulators break when in use, a short is likely to occur. Thus, destructive testing is carried out to determine how much force is required to break the insulators. Suppose you wish to estimate the mean force required to break the insulators to within+ or- 25 pounds with 95% confidence. If on the basis of a study taken the previous year, you believe that the standard deviation is 100 pounds, find the sample size needed. Place you answer, rounded up to the next highest whole number, in the blank. n