Question

At a simple interest, the principal doubles in 10 years. At the same rate, in how many years will the sum be 3 times greater?​

Answer 1

Answer:

20

Step-by-step explanation:

GIVEN:

Amount = 2P

Time = 10 years

FORMULAE USED:

SI = (PRT/100)

Amount = (PRT/100) + P

CALCULATION:

Amount = (PRT/100) + P

2P = (PR/10) + P

⇒ P = (PR/10)

⇒ R = 10%

According to question, Amount = 3P

3P = (10PT/100) + P

⇒ 2P = (PT/10)

⇒ T = 20 years

∴ Time taken to triple the amount is 20 years.

Interest = 2P - P = P = 100% of principle

Time = 10 year

Hence, rate = Interest/Time = 100/10 = 10%

New interest = 3P - P = 2P = 200% of principle

∴ Time = Interest/Rate = 200/10 = 20 Years