There is a simple way to solve this. Let’s start by figuring out the total fixed costs Sally will incur in the 2 years (24 months).

Total fixed costs = $250,000 + 24(4500)
Therefore, Sally must make $358,000 in 24 months to break even.

We’re told that the profit of each store is 30% (70% of revenue is spent on costs).

The weekly revenue per store is $1000, so the monthly revenue is $4000. 30% profit is $1200. Each store will make $28,800 in 24 months.

So, 358,000 / 28800 = ~12.5

Therefore Sally needs a minimum of 13 stores because 12 stores would not generate enough profit for her to break even.


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This is a classic GRE trap. The question tempts you to think about using a formula to find the nth term in a sequence. But looking at the question, you’ll see a pattern that will save you time!

The sequence is structured such that each integer n appears n times:

- 1 appears 1 time.
- 2 appears 2 times.
- 3 appears 3 times.
- 4 appears 4 times.
- And so on.

The sum of the first term is 1
The sum of the first two terms is 3
The sum of the first three terms is 6
The sum of the first four terms is 10

The gap between the sum of terms increases by 1 every time. So, you can quickly list the sums as:

1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105

Now, remember that n appears n times. 91-78 = 13 105-78 = 14. So, the 100th term is 14.