Q51. Find the simple interest on Rs. 1,200 at 6¼% per annum for 4 years.
Formula → S.I. = (P × R × T) / 100
Substitution → (1200 × 25/4 × 4) / 100
Calculation → (1200 × 25) / 100 = 300
Final Answer → Rs. 300
Q52. Find the principal if the simple interest at 5% for 3 years is Rs. 180.
Formula → P = (100 × S.I.) / (R × T)
Substitution → (100 × 180) / (5 × 3)
Calculation → 18000 / 15 = 1200
Final Answer → Rs. 1,200
Q53. Find the time in which Rs. 2,000 will amount to Rs. 2,400 at 5% p.a.
Formula → T = (100 × (A−P)) / (P × R)
Substitution → (100 × (2400−2000)) / (2000 × 5)
Calculation → 40000 / 10000 = 4
Final Answer → Time = 4 years
Q54. A sum of Rs. 1,500 becomes Rs. 1,950 in 6 years. Find the rate of interest.
Formula → R = (100 × (A−P)) / (P × T)
Substitution → (100 × (1950−1500)) / (1500 × 6)
Calculation → (100 × 450) / 9000 = 45000 / 9000 = 5
Final Answer → Rate = 5% p.a.
Q55. Find the simple interest on Rs. 4,800 at 9% for 2½ years.
Formula → S.I. = (P × R × T) / 100
Substitution → (4800 × 9 × 5/2) / 100
Calculation → (4800 × 45) / 200 = 216000 / 200 = 1080
Final Answer → Rs. 1,080
Q56. What sum will yield Rs. 1,200 as simple interest in 4 years at 6% p.a.?
Formula → P = (100 × S.I.) / (R × T)
Substitution → (100 × 1200) / (6 × 4)
Calculation → 120000 / 24 = 5000
Final Answer → Rs. 5,000
Q57. Find the simple interest on Rs. 3,600 at 4⅕% for 3 years.
Formula → S.I. = (P × R × T) / 100
Substitution → (3600 × 21/5 × 3) / 100
Calculation → (3600 × 63) / 500 = 226800 / 500 = 453.6
Final Answer → Rs. 454
Q58. In how many years will Rs. 2,400 produce Rs. 288 as S.I. at 6% p.a.?
Formula → T = (100 × S.I.) / (P × R)
Substitution → (100 × 288) / (2400 × 6)
Calculation → 28800 / 14400 = 2
Final Answer → 2 years
Q59. Find the rate if Rs. 1,500 becomes Rs. 1,710 in 2 years.
Formula → R = (100 × (A−P)) / (P × T)
Substitution → (100 × (1710−1500)) / (1500 × 2)
Calculation → (100 × 210) / 3000 = 21000 / 3000 = 7
Final Answer → 7% p.a.
Q60. Find the principal if S.I. = Rs. 90, R = 9%, T = 2 years.
Formula → P = (100 × S.I.) / (R × T)
Substitution → (100 × 90) / (9 × 2)
Calculation → 9000 / 18 = 500
Final Answer → Rs. 500
Q61. Find S.I. on Rs. 1,800 at 6% for 3 years 4 months.
Convert 4 months = 4/12 = 1/3 year; Total time = 3 + 1/3 = 10/3 years
Formula → S.I. = (P × R × T) / 100
Substitution → (1800 × 6 × 10/3) / 100
Calculation → (1800 × 20) / 100 = 360
Final Answer → Rs. 360
Q62. Find S.I. on Rs. 2,500 at 8% for 1¼ years.
Formula → S.I. = (P × R × T) / 100
Substitution → (2500 × 8 × 5/4) / 100
Calculation → (2500 × 10) / 100 = 250
Final Answer → Rs. 250
Q63. At what rate will Rs. 4,000 become Rs. 4,640 in 4 years?
Formula → R = (100 × (A−P)) / (P × T)
Substitution → (100 × (4640−4000)) / (4000 × 4)
Calculation → 64000 / 16000 = 4
Final Answer → Rate = 4% p.a.
Q64. Find the principal if S.I. = Rs. 216, R = 6%, T = 3 years.
Formula → P = (100 × S.I.) / (R × T)
Substitution → (100 × 216) / (6 × 3)
Calculation → 21600 / 18 = 1200
Final Answer → Rs. 1,200
Q65. Find S.I. on Rs. 1,200 for 5 years at 4⅕% p.a.
Formula → S.I. = (P × R × T) / 100
Substitution → (1200 × 21/5 × 5) / 100
Calculation → (1200 × 21) / 100 = 252
Final Answer → Rs. 252
Q66. Find the rate if Rs. 800 amounts to Rs. 912 in 3 years.
Formula → R = (100 × (A−P)) / (P × T)
Substitution → (100 × (912−800)) / (800 × 3)
Calculation → (100 × 112) / 2400 = 11200 / 2400 = 14/3
Final Answer → 4⅔% p.a.
Q67. Find the principal if the simple interest at 5½% p.a. for 4 years is Rs. 330.
Formula → P = (100 × S.I.) / (R × T)
Substitution → (100 × 330) / (11/2 × 4)
Calculation → (33000 × 2) / 44 = 66000 / 44 = 1500
Final Answer → Rs. 1,500
Q68. Find S.I. on Rs. 2,100 at 7% p.a. for 3 years.
Formula → S.I. = (P × R × T) / 100
Substitution → (2100 × 7 × 3) / 100
Calculation → (2100 × 21) / 100 = 441
Final Answer → Rs. 441
Q69. Find the amount and S.I. on Rs. 900 at 6% p.a. for 2½ years.
Formula → S.I. = (P × R × T) / 100; A = P + S.I.
Substitution → (900 × 6 × 5/2) / 100
Calculation → (900 × 15) / 100 = 135
Final Answer → S.I. = Rs. 135; A = Rs. 1,035
Q70. At what rate will Rs. 2,500 produce Rs. 250 as S.I. in 2 years?
Formula → R = (100 × S.I.) / (P × T)
Substitution → (100 × 250) / (2500 × 2)
Calculation → 25000 / 5000 = 5
Final Answer → 5% p.a.
Q71. Find the time for Rs. 3,000 to earn Rs. 600 as S.I. at 10% p.a.
Formula → T = (100 × S.I.) / (P × R)
Substitution → (100 × 600) / (3000 × 10)
Calculation → 60000 / 30000 = 2
Final Answer → 2 years
Q72. Find S.I. on Rs. 1,200 for 2 years at 7⅓% p.a.
Formula → S.I. = (P × R × T) / 100
Substitution → (1200 × 22/3 × 2) / 100
Calculation → (1200 × 44) / 300 = 52800 / 300 = 176
Final Answer → Rs. 176
Q73. A sum of Rs. 2,400 becomes Rs. 2,760 in 3 years. Find the rate.
Formula → R = (100 × (A−P)) / (P × T)
Substitution → (100 × (2760−2400)) / (2400 × 3)
Calculation → 36000 / 7200 = 5
Final Answer → 5% p.a.
Q74. Find the principal if S.I. = Rs. 180, R = 4½%, T = 2 years.
Formula → P = (100 × S.I.) / (R × T)
Substitution → (100 × 180) / (9/2 × 2)
Calculation → (18000 × 2) / 18 = 36000 / 18 = 2000
Final Answer → Rs. 2,000
Q75. Find S.I. on Rs. 5,000 at 3⅓% for 3 years.
Formula → S.I. = (P × R × T) / 100
Substitution → (5000 × 10/3 × 3) / 100
Calculation → (5000 × 10) / 100 = 500
Final Answer → Rs. 500
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