Help! math prob. Find at what rate of interest per annum will $500 amount to $605 in 3 years?

Question

Is there a way to do it without a calculator? I'm not allowed to use a calculator and I'm finding this particular sum really hard. Is it 10%?

Answer 1

500x^3=605
x=1.0656
interest rate therefore is 6.56%

Answer 2

You would use the compound interest equation and solve for r.

P = future value
C = initial deposit
r = interest rate (expressed as a fraction)
n = # of times per year interest is compounded
t = number of years invested

so P=C(1+r)^t 605=500(1+r)^3 so jsut solve and you get the rate as a decimal *100 to get percent.

Answer 3

Ok, take 500 from 605, thats not hard - 105. Ok, now divide this by three - again not hard and cane be done in the head or on note paper, the answer is 35. Now the final step is to divi...yeh i'm lost try www.bbc.co.uk/schools and check out the revision pages.

Answer 4

Simple Interest:
Interest = Principle x rate x time in years
605 - 500 = (500)(rate)(3)
55 / 1500 = rate
3.7 % = rate

Compound Interest:
A = P(1 + r)^n
605 = (500)(1 + r)^3
605 / 500 = (1 + r)^3
6.6 % = r

Answer 5

7% interest chargable per year
assume that int chargable 10% per annum so interest amt would around 50 x with no. of years so u find ans 150 as 10% for 3 years and amt given in problem is lower than 150 so simple thing reduce rate of int and finally u get the ans i.e & 7% per anuum
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Answer 6

you donot require a calculator to do it.You can do it mentally even.The total amount of interest is $105.Divide $500 by 100 and you get 5.multiply it by 3,the no.of years and yoy get 15.OK? now divide 105 by this 15 and you get your answer,which is incidentally 7%.If you have to do it on paper ,please use the formula I=PRT/100,Where I=Interest, R=Rate of interest and T=time in years,HereI=105,P=$500 T=3 and therefore,105=(500 XRX3)/100 => [105/(500X3)] X100=7% ans.

Answer 7

A=605
P=500
Interest=605-500 = 105

SI=PTR/100

105=500*3yrs*R/100
= 10500=1500*R

R=10500/1500 = 7%

P = principal
T=time
R=rate
SI=simple interest
A=total amount

GoodLuck

Answer 8

you have not explained that you have to use simple interest or compound interest.
with simple interest allready a person has solved it. but if you have to use compund interest then either time is 2 years(if time is 2 years you can find answer without calculator) or you need calculator.