What is the rate of simple interest per annum? (R.B.I., 2004 I. An amount of ` 7500 increases by ` 1125 at the end of one year. II. The principal amount of ` 6000 increases by three times in 20 years. III. Interest accrued on an amount of ` 5200 in ) 3 years is ` 2340.
(a)Any one of the three
(b)Only I
(c)Only III
(d)Either I and II or III only
(e)None of these
Answer
Answer (as printed): A
Explanation
I. gives, $P=₹ 7500$, S.I. $=₹ 1125, T=1$ year. $\therefore \quad R=\left(\frac{100-\text { S.I. }}{P \times T}\right)=\left(\frac{100 \times 1125}{7500 \times 1}\right) \%=15 \%$. Thus, I only gives the answer. II. gives, $P=₹ 6000$, S.I. $=₹ 18000, \mathrm{T}=20 \mathrm{yrs}$. $\therefore \quad R=\left(\frac{100 \times 18000}{6000 \times 20}\right) \%=15 \%$. Thus, II only gives the answer. III. gives, $P=₹ 5200$, S.I. $=₹ 2340, T=3 \mathrm{yrs}$. $\therefore \quad R=\left(\frac{100 \times 2340}{5200 \times 3}\right) \%=15 \%$. Thus, III only gives the answer. ∴ Correct answer is (a).