Data Sufficiency

vijeshimchandran wrote: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?

i. Thomas deposited an additional $4,000 throughout the year
ii. The checking account earned 7 percent simple interest

vijeshimchandran wrote: To check Stat2:

1. In Question they haven't mentioned or hinted anything about amount deposited through out the year.
It should be explicitly mentioned that "he made no deposits" as they have mentioned "made no withdrawals"
See OG13 DS#143 for an example of the wording you could expect on the GMAT


2. Simple Interest is normally for 1 year until and unless specified.
On the GMAT problems you cannot assume things and bring outside knowledge into the question; all the facts are always specified if you look closely.

There could be a possibility where the account earns the interest after 6 months! So essentially with no extra deposits made our guy would have earned interest amount twice in a year. There is no hard-and-fast rule that says simple interests have to be credited annually only.

eg: $2,000 --> 10% simple interest credited per month --> every month he earns an interest of $200 and after 12 months or a year he would have 12*200 = $2400 as the interest amount --> total = 2400+2000 = $4600 after a year
This would be different for Compound interest as we would then consider the "interest on interest" too.

These are some simple interest problem examples from the OG13 Diagnostics Test:
Diag #40 ... invested for one year at p percent simple annual interest
DS #25 ... percent simple annual interest and a different amount at y percent simple annual interest
DS #77 ... this amount earned simple annual interest at the rate of x percent per year,

As you can see they have always mentioned the word annual!