Simple and Compound Interest Quiz-1

As given, simple interest(SI) is 25% of principal(P) and number of year(T) is equal to the rate(R) of percent.

Therefore

SI = 25 % of P

T = R

As we Know,
SI =\frac{P \times R \times T}{100}
So we have
25% of P=\frac{P \times R \times R}{100}
=> \frac{25}{100}\times P=\frac{PR^2}{100}
=> R²=25
=>R=5%.

let the principal be x and rate = r%

Then, difference in between the interest of 5 years and 2 years equals to

800-704 = 96 Rs

So, interest for 3 years = 96 Rs

Hence interest per year = 96/3 = 32 rs

So, interest for 2 years = 2 * 32 = 64 rs

So the principal equals to 704-64= 640 rs

 

Using the formula ,

SI = ( P * R * T)/100 and putting the values as P = 1200, r = 5%, T= 1 yr. The annual interest will be 60rs, after 3 years the total value would be 1200 + 60 * 3 = 1380rs

Amount,A=Rs.1440
Principal,P=Rs.1200
Interest,I=Rs.(1440−1200)=240
R=\frac{240 \times 100}{1200 \times 2} = 10 %

Alternatively,
We can go through a thought processi .e.
1200= =20%↑(240in2years)⇒1400
That means 10% rise in each year

Since compounding is half yearly, it is clearly that the rate of interest changed for 6 months would be 3%. So,
3% of 3300=99
3300 → 3399

Let the rate be R at which Principal P is invested for 2 years.
According to question,
{Interest at Rate (R + 2)}% - (interest at rate R%) = Rs. 60
\frac{(P \times R \times (R +2))}{100}-\frac{P \times 2 \times R}{100}= 60
\frac{2PR +4P - 2PR}{100}=60
4P=60×100
Or,P=\frac{60 \times 100}{4}
Hence,P=Rs.1500

applying

si= (p * r * t)/100

150 = (3000 * 5 * t)/100

150 = (150 * t)

1 = t

applying

si=(p * r *t)/100 * 4 (as it is compounded quarterly)

si = (6400 * 5 * 3)/ 100 * 4

si = 240 rs

For calculating the compound interest we have to first calculate the amount

formula -

A = P(1 + r/100)^t

A = 10000(1 + 8/100)⁴

A= 18,106.39 rs

CI = A-P

= 18,106.39 - 10,000

= 8106.39