On January 1st Thomas deposited $2,000 into an interest bearing checki

E.

(1) Clearly not sufficient as we have no information about the interest rate.

(2) Had I not read statement 1 before, I would have thought this is sufficient. However, we only know there were no withdrawals. What if Thomas deposited more money in the meantime? Clearly not sufficient.

Both statements also aren't sufficient as it would be essential to know the timing of the second deposit.

On January 1st Thomas deposited $2,000 into an interest bearing checking account. If he made no withdrawals, what was the total amount Thomas had in the checking account on December 31st of the same year?

(1) Thomas deposited an additional $4,000 throughout the year.
(2) The checking account earned 7 percent simple annual interest.

__________________________

P = $2000 on Jan 1
Amount on Dec 31 ?

ST 1 : Additional 4000 was spread throughout the year, but we cannot account for the interest earned on (2000 + 4000). So, insufficient

ST 2 : Interest = 7%
This tells you that Interest earned will be 140 making the total amount as 2140
Sufficient.

B should be the answer.

PS: I am a bot confused because of statement A. When I solve ST II, we don't know if there is any investment made throughout the year. So, I came to B after assuming that *no investment* apart from the initial $2000 is done.

So the question is, are we allowed to assume that there was no additional investment in statement B?

So what is the real answer B or E? Please clear the doubt!

The OA is given under the spoiler in the original post.

Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

On January 1st Thomas deposited $2,000 into an interest bearing checking account. If he made no withdrawals, what was the total amount Thomas had in the checking account on December 31st of the same year?

(1) Thomas deposited an additional $4,000 throughout the year.
(2) The checking account earned 7 percent simple annual interest.


In the original condition, there is 1 variable(interest rate), which should match with the number of equations. So you need 1 equation. For 1) 1 equation, for 2) 1 equation, which is likely to make D the answer.
For 1), although Thomas deposited an additional $4,000, it doesn’t say when he did, which is not sufficient.
For 2), you cannot figure out the amount of money additionally deposited, which is not sufficient.
When 1) & 2), you still cannot figure out when he additionally deposited $4,000, which is not sufficient.
Therefore, the answer is E.


 For cases where we need 1 more equation, such as original conditions with “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 59 % chance that D is the answer, while A or B has 38% chance and C or E has 3% chance. Since D is most likely to be the answer using 1) and 2) separately according to DS definition. Obviously there may be cases where the answer is A, B, C or E.

Well, is it actually a GMAT type question? Coz, if it is not stated in statement 2) if any additional deposits were made or not, then it also not stated if the interest accresdited was credited to the same account or some other account OR was there any second holder who could have taken out the money mid way etc etc ...this way the list can become endless. So ARE WE NOT SUPPOSED TO assume that if it is not written then it is not there???

Hi saurabhsavant,

In the original condition, there is 1 variable(interest rate).
However, for 1), $4,000 is added, which increases the number of variables.
Hence, the answer is E.

Happy Studying!
Math Revolution

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