Mean, variance and standard deviation

The sales records for a real estate company are given. From the sample data, the following frequency distributionhas been developed.

Sale Price (1000’s) Number of Houses Sold (frequency)
20-39 1
40-59 2
60-79 4
80-99 2
100-119 1

Calculate the mean, varianceand standard deviationfor the grouped data. Based on the previous answer, how much could the realtor expect to make if he sells 3 houses?

The mean, variance and standard deviation of a real estate company’s number of houses sold is analyzed.