Hi vamkrispk,
If a GMAT question asks you to calculate interest more than once a year, you have to make some minor changes to the Interest Formula (specifically to the interest rate and the number of time-periods).
For example, $1,000 invested at a 10% Compound Interest Rate for 2 years would be:
($1,000)(1.1)^2 = ($1,000)(1.21) = $1,210
If in that same situation, you were asked to calculate interest SEMI-ANNUALLY (meaning TWICE per year), you would then have to cut the interest rate in HALF and DOUBLE the number of time periods:
($1,000)(1.05)^4
It's unlikely that the GMAT would actually require that you to calculate this type of result, but you could do it if needed. It's worth noting that when calculating interest more than once per year, the total amount at the end of all the calculations will be GREATER than if you calculated just once a year (this is generally referred to as "interest on top of interest.").
($1,000)(1.05)^4 = $1,215.51
If you came across a specific Interest Rate question during your studies, then there's a pretty good chance that it's been discussed in the forums here, so you might try "Googling" the question to see if it's been discussed.
Beyond this Quant issue, if you're looking for any additional advice for your studies, then it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long have you studied? How many hours do you typically study each week?
2) What study materials have you used so far?
3) How have you scored on EACH of your CATs (including the Quant and Verbal Scaled Scores for EACH)?
4) What is your overall goal score?
5) When are you planning to take the GMAT?
GMAT assassins aren't born, they're made,
Rich
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Contact Rich at: Rich.C@empowergmat.comThe Course Used By GMAT Club Moderators To Earn 750+ souvik101990 Score: 760 Q50 V42 ★★★★★ ENGRTOMBA2018 Score: 750 Q49 V44 ★★★★★