During the first 11 months of a recent year, a certain charitable organization received an average (arithmetic mean) of $20,600 per month in donations.
how much did the organization receive in donations during december of that year if the average amount of donations per month for the entire year was $21,000?

a) $21,400 b) $21,600 c) $24,000 d) $25,400 e) $25,800

Donation received in December = $ 25,400

Step-by-step explanation:

Given:

Average for 11 months = $20,600

Average for entire year = $ 21,000

Total amount received in first 11 months (A) = $20,600 x 11

                                                                    = $226,600

Total amount received in entire year( 12 months) (B) = $ 21,000 x 12

                                                                                 = $252,000

Therefore,

Amount received in December month = (B) - (A)

                                                                   = $252,000 - $226,600

                                                                   = $ 25,400

b) 36

step-by-step explanation:

18 times 2 is 36