During the first two weeks of January, the total rainfall

[Gmat_mission]

During the first two weeks of January, the total rainfall in Springdale was 15 inches. If the rainfall during the second week was 1.5 times the rainfall during the first week, what was the rainfall during the second week of January?

A. 5 inches
B. 6 inches
C. 9 inches
D. 10 inches
E. 12 inches

[spoiler]OA=C[/spoiler].

I got confused here. What is the equation that solves this PS question? I'd appreciate some help.

[Vincen]

Hi Gmat_mission.

Let's take a look at your question.

Let's call "x" the rainfall in the first week.

"the rainfall during the second week was 1.5 times the rainfall during the first week" implies that the rainfall during the rainfall during the second week was 1.5*x.

"During the first two weeks of January, the total rainfall in Springdale was 15 inches" this implies the following: $$x+1.5\cdot x=15\ \ \ \Rightarrow\ \ \ 2.5x=15\ \ \ \Rightarrow\ \ \ x\ =6.$$ Therefore, the rainfall during the first week was 6 inches and this implies that the rainfall during the second week was 1.5*6=9 inches.

Hence, the correct answer is C .

I hope this explanation may help you.

[Scott@TargetTestPrep]

During the first two weeks of January, the total rainfall in Springdale was 15 inches. If the rainfall during the second week was 1.5 times the rainfall during the first week, what was the rainfall during the second week of January?

A. 5 inches
B. 6 inches
C. 9 inches
D. 10 inches
E. 12 inches

We can let the rainfall in the first week = a and the rainfall in the second week = b and create the following two equations:

a + b = 15

and

b = 1.5a

Substituting, we have:

a + 1.5a = 15

2.5a = 15

a = 6

Thus, the rainfall in the second week was 15 - 6 = 9 inches.

Answer: C