Question

oscar recorded the amount of his monthly electric bill for the first 11 months of the year. an ordered list of the amount, in dollars, of his monthly bills is shown. 79, 98, 99, 99, 102, 105, 119, 122, 124, 125, 127. oscar budgeted $110 per month for his electric bill. what would be the amount of his last monthly bill in order for the mean bill amount to be $110 for all 12 months? a $105 b $109 c $110 d $112 e $121

Explanation:

Step1: Calculate sum of first 11 bills

$79 + 98+99+99+102+105+119+122+124+125+127 = 1109$

Step2: Calculate sum of 12 bills for mean of 110

The mean of 12 bills is 110, so the sum of 12 bills is $110\times12=1320$

Step3: Find the 12th - bill amount

Subtract sum of 11 bills from sum of 12 bills. $1320 - 1109=211$

Answer:

E. $121$