# statistic

posted by
**Nancy** on
.

The distribution of cash withdrawals from the automatic teller machine at a

certain bank has a mean of $500 with a standard deviation of $70. To reduce the

incentives for robbery, the bank puts money into the machine every 12 hours and

it keeps the amount deposited fairly close to the expected total withdrawals for a

12-hour period. If 100 withdrawals were expected in each 12-hour period and

each withdrawal was independent, how much should the bank put into the

machine so that the probability of running out of money was 0.05?