A realtor has 20 residential listings under contract. The following table shows the number of days each of these 20 houses has been on the market as of today. Use the data to complete parts a through e below. 45 24 20 23 4 19 32 23 45 51 55 46 12 41 22 55 24 10 39 60 2 23 75 a. Calculate the mean for this population. (Type an integer or a decimal.)