Question

Please help!!!!

(03.07 MC)
Monica measures the number of bacteria that are living on her petri dish. Each day, she measures the amount of change in the number of bacteria. These amounts
create a geometric sequence. Use the data in the table to determine the sum of the amounts of change in the bacteria after the seventh day.
Day. Amount of Bac
1. 3
2. -6
3. 12
4. -24
Answers
A. -15
B. 15
C. 127
D. 129
I think it is C. 127 but i am not sure please help right away!!!

Answer 1

129

Explanation:

Answer 2

129

Explanation:

Each day, Monica measures the amount of change in the number of bacteria and this number from each day gives a geometric series

3, -6, 12, -24, ...... having first term 3 and the common ratio -2.

Then the sum of the amount of change in the bacteria after the seventh day will be ( 3 - 6 + 12 - 24 + 48 - 96 + 192) = 129 (Answer)