Question

At what rate percent, will Rs 1050 amount to Rs 1380.75 in 4 years 6 months?

Answer 1

Answer :-

Rate percent is 7 %

Solution :-

Given

Principal (P) = Rs. 1050

Amount = Rs. 1380.75

Time (T) = 4 years 6 months = 4 6/12 = 4 1/2 years = 9/2 years

Let the rate of interest be R

We know that

Amount = Principle + Interest

⇒ 1380.75 = 1050 + I

⇒ 1380.75 - 1050 = I

⇒ 330.75 = I

Interest(I) = Rs. 330.75

⇒ PTR/100 = 330.75

Since I = PTR/100

⇒ 1050 * 9/2 * R/100 = 330.75

⇒ 525 * 9 * R = 330.75 * 100

⇒ 4725R = 33075

⇒ R = 33075/4725

⇒ R = 7

Therefore rate percent is 7 %

Answer 2

$\huge{\mathfrak{Answer}}$

$\large{\bf{\underline{Given}}}$

$\large{\sf{Principal (P) = 1050 Rupees}}$

$\large{\sf{Amount = 1380.75 Rupees }}$

$\large{\sf{Time (T) = 9/2 years}}$

$\huge{\bf{Amount = principal + interest}}$

$\large{\sf{1380.75 = 1050 + I}}$

$\large{\sf{1380.75 - 1050 = l}}$

$\large{\sf{330.75 = l}}$

$\huge{\bf{l = Principal × Time × Rate percent}}$

$\large{\sf{1050 × 9/2 × R/100 = 330.75}}$

$\large{\sf{525 × 9 × R = 330.75 × 100}}$

$\large{\sf{4725 R = 33075}}$

$\large{\sf{R = 33075/4725}}$

$\large{\sf{R = 7}}$

$\huge{\boxed{R = 7\:\:percent}}$