A and B borrowed Rs. 3000 and Rs. 3200 respectively at the

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A and B borrowed Rs. 3000 and Rs. 3200 respectively at the same rate of
interest for 2 1 years. If B paid Rs. 40 more interest than A, find the
2
rate of interest.

Rate of interest = r % per annum

SI =	Principal × Time × Rate
	100

According to the question,

	3200 × 5 × r	-	3000 × 5 × r	= 40
	100 × 2		200

⇒ 80r – 75r = 40
⇒ 5r = 40 ⇒ r = 40 ÷ 5 = 8% per annum
Second method to solve this question :

Here, P₁ = Rs. 3000, R₁ = R, T₁ =	5	years
	2

P₂ = Rs. 3200, R₂ = R, T₂ =	5	years
	2

Difference S.I. = Rs. 40

⇒ 40 =	3200 × R × (5 / 2) - 3000 × R × (5 / 2)
	100

⇒ 4000 = 8000R – 7500R
⇒ R = 8%

interest for 2	1	years. If B paid Rs. 40 more interest than A, find the
	2