Tuesday

January 27, 2015

January 27, 2015

Posted by **Anonymous** on Monday, January 21, 2013 at 6:31am.

the compound interest for the same amount for the same period is 410.

find the principal and rate of interest?

- maths-urgently needed -
**Reiny**, Monday, January 21, 2013 at 10:30amlet the principal be P

let the rate be i

simple interest:

I = PiT

400 = 2Pi

Pi = 200 --- P = 200/i

compound interest

P(1+i)^2 - P = 410

P( (1+i)^2 - 1) = 410

P = 410/(1 + 2i + i^2 - 1)

= 410/(i^2 + 2i)

410/(i^2 + 2i) = 200/i

200i^2 + 400i = 410i

200i^2 - 10i=0

i(200i-10) = 0

i = 0 or i = 10/200 = .05

**if i = .05 , then P = 200/.05 = 4000>/b>**

( I rejected i = 0 , since it would make P as undefined)

check:

simple interest

I = prt = 4000(.05)(2) = 400

compound interest

Amount = 4000(1.05)^2 = 4410

interest = 4410-4000= 410 , looks good!

**Answer this Question**

**Related Questions**

computer science - When $1000 is deposit at 5% simple interest, the amount grows...

Visual Basic 2008 Programming - Help! I'm not sure how to start or how calculate...

maths - The difference of compound interest and simple interest on an amount at ...

Kirr - *solve execises by using compounded interest formula Principal $ 700 ...

math - Compute the compound quarterly amount after 1 year for $100 invested at ...

math - Find the total number of compounding periods and interest rate per period...

maths - If an amount of Rs 10,000/- is invested at a simple interest of 12% per ...

Dont I need more info for this Math problem?? - You borrow $2,000 at a rate of 3...

maths - The compound interest on a certain sum for 2 years is Rs 41 and simple ...

math - 1.John deposited $40,000.oo in the bank and earned simple interest of 7% ...