First off, something really basic:
1. For a compound interest problem, I use the formula A=P(1+r/100)^n. I want to know how it works for a qtn that asks for interest compounded SEMI annually? Do you adjust r only or n as well?
2. Here's an interesting one. If you have the OG11th edition, it is on Pg 51, Q11. I really cannot understand this problem. any explanations would be very helpful.
3. OG Diag Pg 51, Q13:
If s and t are positive integers such tha s/t=64.12, which of the following could be the remainder when s is divided by t?
a.2
b.4
c. 8
d.20
e. 45
Can someone explain a not too long method to solve this?
Ans: E
4. Which of the foll is a product of 2 integers whose sum is 11?
a. -42, b. -28, c. 12, d. 26, e. 32
I got this question correctly since I actually used the info regarding the sum ofthe intergers and worked backwards figuring out that the numbers are 14 and -3. However, it seems it can be done using simultaneously eqns as well. i.e. x+y=11, xy= -42. How do you solve for this? Want ot know the other method in case the bulb doesnt strike on G-day.
5. When a square root sign is used on the GMAT, I read that we should use the POSITIVE root only. Is this true?
Prob solving interesting qtns - doubts
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Don't bother with the compound interest formula. The GMAT will never give you a question that requires you to compound more than 2 or 3 times.
But, in general terms, you need to adjust both r and n.
If you're compounding semi-annually at an annual rate of 8%, that's an interest rate (per compounding term) of 4%, and the number of compounds is twice the number of years.
But, in general terms, you need to adjust both r and n.
If you're compounding semi-annually at an annual rate of 8%, that's an interest rate (per compounding term) of 4%, and the number of compounds is twice the number of years.
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Heres how I would do 3.
s/t = 64.12 and s and t are integers
s/t = Whole + remainder/t
Thus
remainder/t = .12
OR
remainder / .12 = t
Since we know t must be an integer, we also know that the remainder / .12 = remainder * 25/3 must also be an integer. Plug in the numbers and viola!
s/t = 64.12 and s and t are integers
s/t = Whole + remainder/t
Thus
remainder/t = .12
OR
remainder / .12 = t
Since we know t must be an integer, we also know that the remainder / .12 = remainder * 25/3 must also be an integer. Plug in the numbers and viola!
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For 4 you could do two things
A) Factor trees, then try out all the possible combinations (its actually not that bad)
B) Simultaneous equations and quadratics. This one took me a bit longer than the first method (because I'm not good at large multiplications and square roots) but they are pretty much a toss up. If you are good with quadratics then do that.
A) Factor trees, then try out all the possible combinations (its actually not that bad)
B) Simultaneous equations and quadratics. This one took me a bit longer than the first method (because I'm not good at large multiplications and square roots) but they are pretty much a toss up. If you are good with quadratics then do that.
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For the compound interest you have to adjust both rate and time.
You can make use of this formula instead:
A= P( 1 + r/n )^(nt)
where: P= principal
r = Annual rate of interest
(IMPORTANT) n = No of times the interest is compounded per year
t = No of years
so if interest is compounded quarterly then n=4
Thanks
Komal
You can make use of this formula instead:
A= P( 1 + r/n )^(nt)
where: P= principal
r = Annual rate of interest
(IMPORTANT) n = No of times the interest is compounded per year
t = No of years
so if interest is compounded quarterly then n=4
Thanks
Komal
Thanks Komal, so that means for a qtn, for e.g.
5000, compounded quarterly for 2 yrs, @8%
= P(1+r/4)^8 correct?
=5000(1+0.08/4)^8
I heard that the GMAT normally doesnt give high compounds (i.e. more than a year) but I just wanted to have the concept down correctly.
5000, compounded quarterly for 2 yrs, @8%
= P(1+r/4)^8 correct?
=5000(1+0.08/4)^8
I heard that the GMAT normally doesnt give high compounds (i.e. more than a year) but I just wanted to have the concept down correctly.