Question

Abena wanted to buy a bag and had saved for 8 consecutive weeks. She saved $2 in the first week, $4 in the second week, $6 the third week, $8 in the fourth week, and so until the eighth week. How much did the bag cost if her entire savings at the end of the eighth week was spent on buying the bag?

A. $20
B. $36
C. $64
D. $144

Answer 1

The bag cost $72.

Step-by-step explanation:

To find out how much the bag cost, we need to add up the amounts saved in each of the 8 consecutive weeks. The amounts saved increase by $2 each week, starting from $2 in the first week and ending with $16 in the eighth week. We can find the sum of these amounts using the formula for the sum of an arithmetic series:

Sum = (n/2)(first term + last term)

Plugging in the values, we have:

Sum = (8/2)(2 + 16) = 4(18) = 72 dollars

Therefore, the bag cost $72.