Simple Interest- Aptitude Questions and Answers

 Two equal amount were lent on simple interest of 7% and 5% respectively. The interest earned on both of them adds 960 rupees in 4 years. What is the total amount lent out? A) 3500 B) 2500 C) 2000 D) 3000 Correct Answer : 2000 Explanation :Let the amount is X As is given, (X*7*4 / 100) + (X*5*4 / 100) =960 28*X/100 + 20*X/100= 960 X=960*100 / 48 =2000 Post/View Answer Post comment Cancel Thanks for your comment.! Write a comment(Click here) ...
 A sum of money doubles in 10 years. In how many years will it become four times at the same rate of simple interest? A) 30 years B) 50 years C) 20 years D) 25 years Correct Answer : 30 years Explanation :Let Principal = P, Rate = R% per annum, Time = n years. Simple Interest (SI) = (P*R*T )/100 money doubles in 10 years then, 2P=P+(P*R*10 )/100 P=(P*R )/10 R=10 it become four times at the same rate then, 4P=P+(P*10*T )/100 3P=(P*T )/10 So, T=30 A principle becomes twice in 5 years. In how many years it will become 10 times? A) 45 years B) 25 years C) 50 years D) None of these Correct Answer : 45 years Explanation :A = P(1 + rt/100) P = principal r = rate in % t = time in years A principle becomes twice in 5 years, that is A= 2P, T=5 ,R=? 2P= P + PR * 5/100 2P-P = PR/20 P= PR/20 R= 20 now when the money 10 times, that is A= 10P , R= 20 , T=? 10P = P + PRT/100 = P + P * 20 * T /100 10P-P = PT/5 9P = PT/5 T= 45 After 45 years the money becomes 10 times If a sum becomes Rs.18300 in 15/2 years at the rate of 7% per annum, find the sum? A) Rs. 10000 B) Rs. 12000 C) Rs. 14000 D) Rs. 15000 Correct Answer : Rs. 12000 Explanation :Simple Interest (SI) = (P*R*T )/100 Amount, A = P + SI = P + (P*R*T)/100 Let the Orignal amount is P then ,R=7 and T= 15/2 years 18300 = P +[P* 7* (15/2) /100 ] 18300 = P + [ (P* 7* 15) / 200 ] 18300 = P + [ 21*P / 40 ] 61*P=18300 * 40 P=300*40 P=12000 Hence the Amount was 12000 Find the sum of money will amount to Rs 900 in 4 years at 5 % per annum on simple interest? A) Rs 750 B) Rs 650 C) Rs 500 D) Rs 550 Correct Answer : Rs 750 Explanation :Let Principal = P, Rate = R% per annum, Time = n years. Simple Interest (SI) = (P*R*T )/100 Amount =P + (P*R*T )/100 Thus, 900 = P + (P*5*4 )/100 ⇒ 900 = 6*P / 5 ⇒ P = ( 900 x 5) /6 = Rs 750 At what rate percent per annum will a sum of money doubles in 8 years? A) 12 % B) 12.5 % C) 13 % D) 15 % Correct Answer : 12.5 % Explanation :Let Principal = P, Rate = R% per annum, Time = n years. Simple Interest (SI) = (P*R*T )/100 Amount =P + (P*R*T )/100 Thus, 2P =P + (P*R*8 )/100 ⇒ P= P*R*8 / 100 ⇒ R = 100 /8 So, R=12.5% A sum of money amounts to Rs. 702 in 2 years and Rs. 783 in 3 years. The rate percent is ? A) 12% per annum B) 13% per annum C) 14% per annum D) 15% per annum Correct Answer : 15% per annum Explanation :Let Principal = P, Rate = R% per annum, Time = n years. Simple Interest (SI) = (P*R*T )/100 S.I. for 1 year = Rs. (783 - 702) = Rs 81 S.I. for 2 years = Rs. (81 x 2) = Rs. 162 Then, Sum P = Rs. (702 - 162) = Rs. 540 So, Required rate R =(100 x SI) / (P x T) = (100 x 162) / (540 x 2) % = 15% Rahul borrowed Rs. 8000 from Mr. Chobey at simple interest. After 2 years he paid Rs. 800 more than what be borrowed and thus cleared the loan. What was the rate of interest ? A) 6 B) 8 C) 5 D) None of these Correct Answer : 5 Explanation :Let Principal = P, Rate = R% per annum, Time = n years. Simple Interest (SI) = (P*R*T )/100 Then, Rate R = (SI x 100) / (P*T) = (800 x 100) / (8000 x 2) = 5% Deepak invested an amount of 21250 for 6 yr. At what rate of simple interest, will he obtain the total amount of 26350 at the end of 6 yr ? A) 4% pa B) 5% pa C) 8% pa D) 12% pa Correct Answer : 4% pa Explanation :Let Principal = P, Rate = R% per annum, Time = n years. Simple Interest (SI) = (P*R*T )/100 Then, SI = 26350 - 21250 = 5100 R= (SI x 100) / (P * T) = (5100 x 100) / (21250 x 6) So, Rate R= 4% A sum of Rs.3900 is lent out in two parts in such a way that the simple interest on one part at 10% for 5 years is equal to that on another part at 9% for 6 years. Find the sums. A) 1950, 1950 B) 2025, 1875 C) 1800, 2100 D) 1950, 1800 Correct Answer : 2025, 1875 Explanation :Let Principal = P, Rate = R% per annum, Time = n years. Simple Interest (SI) = (P*R*T )/100 Let, Principle lent out in two parts as x and 3900-x Then As given, x * 10* 5= (3900-x) * 9 * 6 25x = 3900*27 - 27x 52x=3900*27 x=2025 other part is x=2025 other part is 3900-x = 3900-2015 =>1875 The sum which amounts to Rs 889 in 3 years at the rate of 9% per annum simple interest is Rs_____? A) 700 B) 800 C) 600 D) 160 Correct Answer : 700 Explanation :Simple Interest (SI) = (P*R*T )/100 Amount, A = P + SI = P + (P*R*T)/100 Let the Orignal amount is P then , 889 = P +( P* 9* 3)/100 127*P=889*100 P=88900/127 P=700 Hence the Amount was 700 Mr. Thomas invested an amount of Rs. 13,900 divided in two different schemes A and B at the simple interest rate of 14% p.a. and 11% p.a. respectively. If the total amount of simple interest earned in 2 years be Rs. 3508, what was the amount invested in Scheme B? A) 7000 B) 6500 C) 6400 D) 6000 Correct Answer : 6400 Explanation :Let the sum invested in Scheme A be Rs. x , And that in Scheme B be Rs. (13900 - x). Then, [(x * 14 * 2) / 100] + {[(13900 - x) * 11 * 2] / 100 } = 3508 (28x / 100) + [(13900 - x) * 22] / 100 = 3508 28x + [(13900 - x) * 22] = 3508 * 100 28x + [(13900 - x) * 22] = 350800 28x + 305800 – 22x = 350800 28x – 22x = 350800 – 305800 6x = 45000 x = 7500 So, sum invested in Scheme B = Rs. (13900 – 7500) = Rs. 6400 In what time will rupees 1860 amount to rupees 2641.20 at simple interest of 12%per annum? A) 3 years B) 7/2 years C) 4 years D) 9/2 years Correct Answer : 7/2 years Explanation :SI = 2641.20 - 1860 = 781.20 781.20 = (1860* 12* time) / 100 Time = 78120 / (1860* 12) =42 / 12 =7 / 2 John has invested amount at 10% per annual on simple interest. Four years later, the amount goes up to 770 rupees with interest, accordingly what was the amount? A) 650 B) 350 C) 550 D) 500 Correct Answer : 550 Explanation :Let the amount is X Then, after 4 years SI =770 - X (770 - X) = (X* 10* 4) / 100 (770 - X) = X*2 / 5 2*X = 3850 - 5*X 7*X = 3850 X = 550 Ravi invested amount P in a scheme A offering simple interest at 10% per annum for two years. He invested the whole amount he received from scheme A, in another scheme B offering simple interest at 12% per annum for five years. If the difference between the interests earned from schemes A and B was 1300, what is the value of P? A) 2500 B) 2000 C) 3000 D) 3500 Correct Answer : 2500 Explanation :SI from scheme A = P*10*2 /100 =P/5 Amount received from scheme A =P + P/5 = 6P/5 Now, SI from scheme B= (6P/2)*12*5 /100 = 18P/25 According to the question, 18P/25 - P/5 = 1300 13P/25=1300 P=2500 A sum of money was invested at a certain rate of simple interest for 4 years. Had the sum been invested at a rate 3% higher than the actual rate, the interest earned would have been 720 Rs more. Find the sum initially invested? A) 24000 B) 18000 C) 6000 D) 5400 Correct Answer : 6000 Explanation :Let the sum is p , rate r and time t , then simple interest = p*r*t /100 As is given p*(r+3)*4/100 - p*r*4 /100 =720 p*4*(r+3 - r) = 720*100 p*12 = 72000 p= 6000 The rate of simple interest on a sum of money is 6 percent per annum for first 3 years, 8 percent per annum for the next 5 years and 10 percent per annum for period beyond 8 years. If simple interest accrued by the sum for a total period of 10 years is Rs 1560, What is the sum? A) Rs 1500 B) Rs 3000 C) Rs 2000 D) Rs 5000 Correct Answer : Rs 2000 Explanation :Let the sum is x as given, (x*3*6)/100 +(x*8*5)/100 +(x*10*2)/100 =1560 18x + 40x + 20x =156000 78x =156000 x =2000 Hence sum is 2000