Solve the problem.
-John does 10 pushups on the first day of a 30-day month, and then increases the number of pushups by 3 pushups a day. How many pushups has he done by the end of the month?
A)1595 pushups
B)1605 pushups
C)1695 pushups
D)1650 pushups

Question

Quizplus · Accepted Answer

John's pushups form an arithmetic sequence with the first term a1 = 10 and the common difference d = 3. The nth term is given by an = a1 + (n-1)d. For 30 days, the last term a30 = 10 + (30-1)*3 = 97. The sum of an arithmetic sequence is S = n/2 * (a1 + an). So, S = 30/2 * (10 + 97) = 15 * 107 = 1605 pushups.

Solve the Problem. -John Does 10 Pushups on the First Day of a Day