A door to door vacuum cleaner salesman finds that for each housevisit he has a 20% chance to sell the vacuum cleaner. Today heplans to visit 3 houses. Assume that customers' purchase behavioris independent. Use Excel to find the following:

(a) Find the probability that he can sell at least 1cleaner.
(b) Find the expected number of vacuum cleaners he can sell fortoday.
(c) Find the variance of the number of cleaners.
(d) Find the standard deviation of the number of cleaners.