Query about Question 4 from "GRE Mini Exam #1" [1187]

GRE GRE Quant Problem Solving
1

https://www.gregmat.com/quizzes/quiz/gre-mini-exam-1 (Question 4)

Hi,
as per the solution n will equal to 9. but won’t the formula be 3.(2)^n-1 where n is the number of days?
So for first day we can say, number of bacteria in dish would be 3
then second day 6, …so on. Accordingly on the 10th day the numbers gonna be 1536

2

Hi

There were 3 bacteria at the beginning of first day.

And it doubles at the end of the day.

Therefore, at the end of the first day, there’ll be 3×2 = 6, not 3.