Cathy is a door-to-door salesperson. When she goes to a house, the probability that she will make a sale is 0.23. This probability is constant and the probability that Cathy will make a sale at a house is independent of sales at other houses. Calculate the variance in the number of sales Cathy will make in a day if each day she approaches 56 houses. Give your answer to 2 decimal places. Variance in number of sales = S