13. To determine p, the proportion of time that an airline operator is busy answering customers, a supervisor observes the operator at times selected randomly and independently from other observed times. Let Xi = 1 if the ith time the operator is observed, he is busy; let Xi = 0 otherwise. For large values of n, if (1/n)

Pn i=1 Xi’s are taken as estimates of p, for what values of n is the error of estimation at most 0.05 with probability 0.96?