What is the rate of interest p.c.p.a.? I. An amount doubles itself in 5 years on simple interest. II. Difference between the compound interest and the simple interest earned on a certain amount in 2 years is Rs. 400. III. Simple interest earned per annum is Rs. 2000

Correct Answer: 824.32

Correct Answer: Rs.16400

Correct Answer: 4460

Explanation:

Let the sum be Rs.P.then
P(1+R/100)^3=6690?(i) and P(1+R/100)^6=10035?(ii)
On dividing,we get (1+R/100)^3=10025/6690=3/2.
Substituting this value in (i),we get:
P*(3/2)=6690 or P=(6690*2/3)=4460
Hence,the sum is rs.4460.

Correct Answer: 2 years

Correct Answer: 20000

Explanation:

Let sum=Rs.x

 

C.I. when compounded half yearly =  x 1 + 10 100 4 - x = 4641 10000

 

C.I. when compounded annually = x 20 100 2 - x = 11 25

  4641 10000 x - 11 25 x = 482

 

=> x=20000

Correct Answer: 3430

Explanation:

Let each installment be Rs.x. Then, 

(P.W. of Rs.x due 1 year hence) + (P.W of Rs.x due 2 years hence) + (P.W of Rs. X due 3 years hence) = 7620.

 

x 1 + 50 3 x 100 + x 1 + 50 3 x 100 2 + x 1 + 50 3 x 100 3 = 7620

 

  6 x 7 + 36 x 49 + 216 x 343 = 7620

 

  294 x + 252 x + 216 x = 7620 x 343

 

 => x = 3430

 

 Amount of each installment = Rs.3430

Correct Answer: Rs.8000

Explanation:

Compound Interest on P at 10% for 2 years when interest is compounded half-yearly

 

= P 1 + R 2 100 2 T - P = P 1 + 1 20 4 - P = P 21 20 4 - P

 

Simple Interest on P at 10% for 2 years =  P R T 100 = P × 10 × 2 100 = P 5

 

Given that difference between compound interest and simple interest = 124.05

  P * 21 20 4 - P - P 5 = 124 . 05

 

=> P 21 20 4 - 1 - 1 5 = 124 . 05

 P=8000

Correct Answer: Rs.1261

Explanation:

Clearly, Rate = 5% p.a .,

Time = 3 years

S.I =Rs.1200.

So,Principal

=Rs.(100 x 1200/3x5)

=Rs.8000.

 

Amount

=Rs.[8000 x (1+5/100)³]

=Rs(8000x21/20x21/20x21/20)

= Rs.9261

 

C.I

=Rs.(9261-8000)

=Rs.1261.

Correct Answer: 5400

Explanation:

Interest for 1 year is the same whether it's simple interest or the compound interest.

Now interest of third year = 8575 - 7350 = 1225; means principal for this interest is 7350 if comound interest is takenIf 7350 is the principal interest = 1225

if 100 is the principal interest =(1225/7350) * 100 = 50/3 %

When a thing increases for two successive times the overall increase on initial amount = a + b + (a * b)/100

Therefore overall interest for two years = 50/3 + 50/3 + [(50/3)*(50/3)]/100 = 325/9 %

Therefore amount after 2 years = 100 + 325/9 = 1225/9

If 1225/9 is the amount principal =100

if 7350 is the amount principal =(900/1225)*7350 =5400

So sum = 5400; Rate = 50/3 %

Correct Answer: Rs.2522

Explanation:

Principal = Rs.16,000;

Time=9 months = 3 quarters;

Amount

=Rs.[16000x(1+5/100)³] =[16000x21/20x21/20x21/20]

= Rs.18522.

 

C.I

= Rs.(18522 - 16000)

= Rs.2522.