Question

A sum of money doubles itself in 20 yrs, in how many years would it treble itself?

Answer 1

Answer:

30 years.

Step-by-step explanation:

Supposed,, we have 100 taka. it will 200 after 20 years.. now we have 200 and it will 300 after 30 years.

Answer 2

Question :

A sum of money doubles itself in 20 yrs, in how many years would it treble itself?

Answer :

In 40years, the sum of money would treble itself.

Given :

Time taken by the Principal amount to double itself = 20years

To find :

No.of years when the principal amount would treble itself

Solution :

Let the Principal be Rs.P

According to the problem ,

Amount (A) = 2P

Time (T) = 20 years

We know,

Simple interest (SI) = A - P

= 2P - P

= P

We also know ,

SI = PRT / 100

Rate of interest (R) is not known

Therefore, P = (P×R×20)/100

=> P = 20 PR /100

=> 100 P = 20 PR

=> 100P/P = 20 R

=> 100 = 20R

Hence, R = 100/20

= 5% p.a

Hence,

When Principal = P , R = 5 % p.a ,

Amount = 3P

SI = 3P - P

= 2P

According to the problem,

2P = P×5×T/100

=> 2P/P = 5T/100

=> 2 × 100 = 5T

=> 200 = 5T

Or, T = 200/5

T = 40

Hence, in 40years, the sum of money would treble itself.

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