Larry saves x dollars per month. Will Larrys total savings one year

Question

Larry saves x dollars per month. Will Larry’s total savings one year from now exceed his present savings by at least $500 ? (Assume that there is no interest.)

(1) In 6 months Larry's total savings will be $900.
(2) In 3 months Larry's total savings will exceed his present savings by $150.

ID: 700138
DS21223

Bunuel · Accepted Answer

Larry saves x dollars per month. Will Larry’s total savings one year from now exceed his present savings by at least $500 ? (Assume that there is no interest.)

Let's say Larry's present savings is  y .

Question asks:

Is  12x+y>y+500 ?

Is  12x>500 ?

(1) In 6 months Larry's total savings will be $900.

The above implies that  y+6x=900 , which is not sufficient to say whether  12x>500  (or whether  6x>250 ).

(2) In 3 months Larry's total savings will exceed his present savings by $150.

The above implies that  y+3x=y+150 , whic gives  x=50 . Thus,  12x = 600 > 500 . Sufficient.

Answer: B.

laddaboy · Answer

Given : Larry saves x $ per month

From 
1) Larry saves 150$ per month, hence in 12 months he saves 1800$. But we don't have info about his present savings. 
Not Sufficient.

2) In 3 months Larry's savings exceed his saving by 150$. Now since it is given Larry saves an constant amount every month, it is safe to assume in 12 months Larry's savings will exceed his previous savings by 600$. 
Sufficient.

Basshead · Answer

(1) In six months, Larry's total savings will be $900. We don't know what his current savings are. It could be that his current savings are $888; therefore he only exceeds his present savings by $12. Or it could be that his current savings are $300 and he saves $100 each month for the next 6 months. INSUFFICIENT.

(2) In 3 months his savings will increase by $150, meaning each month he saves $50. We can conclude that his total savings for the year will exceed his present savings by $600. SUFFICIENT.

Answer is B.

CWC · Answer

Agreed statement 1 is insufficient, but how do you know from statement 1 that he saves $150/month?

Would both of the following scenarios (and all of the ones in between) be possible?

Scenario 1:
he originally had $896 in savings... he saved $1 a month for 6 months... he now has $900

Scenario 2:
he originally had $0 in savings... he saved $150 a month for 6 months... he now has $900

if both could be true, then he could have wildly different amounts after 12 months

Scenario 1: $906... $12 more than when he started
Scenario 2: $1800... $1800 more than when he started

therefore, insufficient

Shin0099 · Answer

Hey there! 
Stupid question, but im marked from the current gmatclub-olympia one with the parrot and the nittygritty wording.
Its trivial, that under the assumption that none of the money is spent, B is correct.
But having no informations about the actual the usage of the savings/possible cashflows, i would go with E.

Why do we assume different?

Bunuel  Thank you very much in advance and for your general work in this forum!

MarkGMATMentor · Answer

This problem illustrates a pattern that comes up with some frequency:  You can often find an increase or decrease without knowing the initial or final values.

At first, it might appear that to answer the question you need to know Larry’s present savings and his savings one year from now. You could then subtract one from the other and compare the result to $500. While this thinking isn’t wrong, it means you would need to find two unknowns, and makes no use of the given variable x.

Instead, let’s try to use x. If Larry saves x dollars per month, then he saves 12x dollars per year. Thus, 12x represents the  increase in savings  from the present to one year from now. So you can restate the question more simply as:

Is  {12x}\geq{500}  ?

Statement 1:

You know Larry’s savings at certain point in time, but you don’t know how much he’s saving each month. x could be $100 or $1, for example, giving you both a YES and a NO answer.  Insufficient.

Statement 2:

If Larry saves $150 in 3 months, then he's saving $50 / month. In other words, x = 50. Thus, he saves 12(50) = $600 in a year, giving a definite YES answer to the question.  Sufficient . The answer is B.

Note, however, that you didn’t even need to calculate. Statement 2 tells you how much Larry is saving each month, so either that will be enough to increase his savings by at least $500 in a year (an answer of YES) or it won’t (an answer of NO).

Either way you have a definite answer, so either way you know that the statement is sufficient. While the calculation here is relatively easy, this is a shortcut that can save you time, especially on more complex questions.

The trap here is reading the question and thinking that you need to know both Larry’s current savings and his savings one year from now to calculate the increase. In that case, you might think the answer is C, because only with both statements together can you find those values.

But in fact, you don’t need the initial or final values to solve the question.  In this question and others that ask for an increase or decrease, knowing the incremental value alone is often enough to answer the question definitively.

rashminuligonda · Answer

In such questions, if on basis of statement 1 if the answer is yes and on basis of statement 2 the answer is 2. ( no additional inferences can be drawn based on both statements together) then should we choose option D or E?

Bunuel · Answer

In Data Sufficiency questions, the two statements cannot contradict each other. So if one statement gives a definite Yes answer and the other gives a definite No answer, then either your solution is incorrect or the question itself is flawed.

For a valid DS question, the statements must be consistent with each other.

Larry saves x dollars per month. Will Larrys total savings one year

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GMAT Data Sufficiency (DS) Questions

Larry saves x dollars per month. Will Larrys total savings one year

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