17. In what time will the interest on Rs 2500 be Rs. 500 at the rate o

1.	17. In what time will the interest on Rs 2500 be Rs. 500 at the rate of 10% per year?18. At what rate of interest will a sum of money double in 20 years?[Hint: in 20 years Rs. 100 will become 2×100 = Rs 200. So interest is 200-100]
Answer» Answer: 17. 2 Years. 18. 5% Step-by-step explanation: 17. Given: Simple Interest = Rs. 500 Principal = Rs. 2500 Rate = 10% p.a. Asked: Time = ? Solution: We know that, Simple Interest = $\frac{PRT}{100}$ 500 = 2500 × $\frac{10}{100}$ × Time Time = $\frac{500 × 100}{2500 × 10}$ Time = 2 years __________________________________________________________ 18. Given: Time = 20 years Let Principal be 'x', then Amount = 2X Simple Interest = Amount - Principal ⇒ 2x - x ⇒ x Simple Interest = x Now we know that, Simple Interest = $\frac{PRT}{100}$ x = $\frac{x × R × 20}{100}$ R% = $\frac{x × 100}{x × 20}$ Rate% = 5% = At the rate of 5% a SUM of money double in 20 years.

17. In what time will the interest on Rs 2500 be Rs. 500 at the rate of 10% per year?18. At what rate of interest will a sum of money double in 20 years?[Hint: in 20 years Rs. 100 will become 2×100 = Rs 200. So interest is 200-100]

Answer»

Answer:

17. 2 Years.

18. 5%

Step-by-step explanation:

17. Given:

Simple Interest = Rs. 500

Principal = Rs. 2500

Rate = 10% p.a.

Asked:

Time = ?

Solution:

We know that,

Simple Interest = $\frac{PRT}{100}$

500 = 2500 × $\frac{10}{100}$ × Time

Time = $\frac{500 × 100}{2500 × 10}$

Time = 2 years

__________________________________________________________

18. Given:

Time = 20 years

Let Principal be 'x',

then Amount = 2X

Simple Interest = Amount - Principal

⇒ 2x - x

⇒ x

Simple Interest = x

Now we know that,

Simple Interest = $\frac{PRT}{100}$

x = $\frac{x × R × 20}{100}$

R% = $\frac{x × 100}{x × 20}$

Rate% = 5%

= At the rate of 5% a SUM of money double in 20 years.