Hello and welcome to exampundit. Here is a set of Quantitative Aptitude Quiz on Compound Interest for Prelims exam of SBI Clerk 2018.   1. A certain sum of money becomes an amount at the certain rate of interest of C.I to Rs 6000 in 2 years and to Rs 7500 in 3 years. Find the sum of money & rate of interest? A) Rs 3740 B) Rs 3840 C) Rs 3940 D) Rs 3640 [su_spoiler title="Answer & Solutions" style="fancy" icon="arrow-circle-1"] Option: B Explanation: S.I on Rs 6000 for 1 year=7500-6000=1500 Rate=(100*S.I/P*T)%=100*1500/6000*1=25% Let the sum be Rs x then for two years A=P(1+r/100)^n Or 6000=x(1+25/100)^2 Or 6000=x(5/4)^2 Or x=(6000*16)/25 Or x= Rs 3840 [/su_spoiler]   2. The C.I on a certain sum for 2 years at 20% per annum is Rs 880. The S.I on the same sum for double the time at half the rate per cent per annum is? A) Rs 800 B) Rs 1000 C) Rs 1200 D) Rs 1600 E) Other than those given as options [su_spoiler title="Answer & Solutions" style="fancy" icon="arrow-circle-1"] Option: A Explanation: 20% per annum compound rate of interest for 2 years is equivalent to 20+20+(20*20)/100=44% 10% simple rate of interest for 4 years is equivalent to 40% Now,44% is equivalent to 880 Therefore 40% is equivalent to 800 [/su_spoiler]     3. The SI accrued on an amount of Rs 22600 at the end of 2 years is Rs 4520. What would be the C.I accrued on the same amount at the same rate of interest for the same period? A) Rs 4645 B) Rs 4746 C) Rs 4505 D) Rs 4795 E) None Of These [su_spoiler title="Answer & Solutions" style="fancy" icon="arrow-circle-1"] Option: B Explanation: Rate=(4520*100)/(22600*2) C.I=(22600*110*110)/10000 – 22600 =27346-22600=Rs 4746 [/su_spoiler]   4. The C.I (compounded anually) on Rs 9100 for 2 years at R% pa is Rs 6279. Had the rate of interest been(R-15)%,what would have been the compound interest on the same sum of money for the same time? A) Rs 6554.35 B) Rs 2132.50 C) Rs 2934.75 D) Rs 3105.25 E) Rs 2748.65 [su_spoiler title="Answer & Solutions" style="fancy" icon="arrow-circle-1"] Option: C Explanation: C.I=6279 Now,?% of 9100=6279 Therefore x=(6279/9100)*100=69% Hence, R=30% Now,new rate=30-15=15% Equivalent rate of 15% compound rate of interest for 2 years =15+15+(15*15)/100 =30+2.25=32.25% Now,32.25% of 9100=(129/400)*9100=Rs 2934.75 [/su_spoiler]     5. The difference between the amount of C.I and S.I accrued on an amount of Rs 11500 in 2 years is Rs 93.15. What is the rate of interest pcpa? A) 6% B) 11% C) 8% D) 9% E) None Of these [su_spoiler title="Answer & Solutions" style="fancy" icon="arrow-circle-1"] Option: D Explanation: Difference=PR^2/100^2 Or 93.15=(11500*R^2)/10000 Or R^2=81 Or R=9% [/su_spoiler]   6. The S.I accrued on a certain sum is Rs 8388 in 6 years at the rate of 12% per annum. What would be the accrued C.I on the sum at the rate of 10% per annum in 2 years? A) Rs 2240.6 B) Rs 2886.6 C) Rs 2446.5 D) Rs 2552.5 E) Other than the given options [su_spoiler title="Answer & Solutions" style="fancy" icon="arrow-circle-1"] Option: C Explanation: Principal=(8388*100)/12*6=11650 Therefore C.I=(11650*110*110)/(100*100) – 11650 =14096.50-11650=Rs 2446.50 [/su_spoiler]   7. Ramesh has a sum of Rs 12,000 deposited at C.I and it becomes double after 5 years. After 20 years,it will become: A) Rs 96000 B) Rs 120000 C) Rs 124000 D) Rs 192000 E) None Of These [su_spoiler title="Answer & Solutions" style="fancy" icon="arrow-circle-1"] Option: D Explanation: Let the rate be R. So, 12000*(1+R/100)^5=24000 Or (1+R/100)^5=2 Or ((1+R/100)^5)^4=2^4=16 Or P(1+R/100)^20=16P Or 12000(1+R/100)^20=16*12000=192000 [/su_spoiler]   8. The least number of complete years in which a sum of money put out at 20% C.I will be more than doubled is? A) 3 B) 4 C) 5 D) 6 [su_spoiler title="Answer & Solutions" style="fancy" icon="arrow-circle-1"] Option: B Explanation: P(1+20/100)>2P or (6/5)^n>2 Now,(6/5*6/5*6/5*6/5)>2 So,n=4 years [/su_spoiler]   9. What sum of money at C.I will amount to Rs 2249.52 in 3 years if the rate of interest is 3 % for the first year,4% for the second year and 5% for the 3rd year? A) 2000 B) 2500 C) 3200 D) 1900 [su_spoiler title="Answer & Solutions" style="fancy" icon="arrow-circle-1"] Option: A Explanation: The general formula that can be applied for this question is : A=P(1+r1/100)(1+r2/100)(1+r3/100)..... Where A=Amount, P=Principal and r1,r2,r3 are the rates of interest for different years. Thus, 2249.52=P(1+3/100)(1+4/100)(1+5/100) Or 2249.52=P(1.03)(1.04)(1.05) Or P=2249.52/(1.03*1.04*1.05)=Rs 2000 [/su_spoiler]   10. If the difference between the S.I and C.I on a certain sum of money for 3 years at 5 percent per annum is Rs 122. Find the sum? A) 17000 B) 16000 C) 18000 D) 19000 [su_spoiler title="Answer & Solutions" style="fancy" icon="arrow-circle-1"] Option: B Explanation: Sum=(Difference)*100^3/R^2*(300+R) =122*100*100*100/25*305=Rs 16000 [/su_spoiler]   Regards Team Exampundit