Weeks. Weeks. 52 : 17 :: £56 6s. £18 8s. 1d. Interest for 17 weeks d. £ s. (5) Find the Interest of £173 15s. from March 5 to October Now, from March 5 to October 10 (not reckoning the first day), we have 219 days. And Interest for 365 days (1 yr.) = £8 13s. 9d. Therefore, by Rule of Three,— Days. Days. 365 : 219 :: £8 13s. 9d. : £5 4s. 3d. Interest from Mar. 5 to Oct. 10 = £5 4s. 3d. Exercise 1. (1) Find the simple interest on £945 10s. for 4 years at 5 per cent. (2) Find the amount of £575 at 3 per cent. for 6 years. (3) Find the interest on £1061 15s. at 21 per cent. for 5 years. (4) Find the interest on £117 17s. 2d. at 10 per cent. for 6 years. (Note. The following examples are all taken from Government Examination Papers.) (5) Required the amount of £537 16s. 8d. in 4 years at 2 per cent., simple interest. (6) Find the simple interest and amount of £7506 for 7 years at 4 per cent. per annum. (7) Find the amount of £325 16s. 8d. at 4 per cent., simple interest, in 3 years. (8) What would £120 10s. amount to in 2 years at 4 per cent. ? (9) What is the simple interest on £185 for 4 years at 4 per cent. per annum ? (10) Find the amount of £220 for 7 months at 3 per cent. per annum. (11) Find the simple interest on £888 for 4 years at 3 per cent. (12) Find the simple interest on £2500 for 11 years at 5 per cent. per annum. (13) Find the simple interest on £90,010 for 7 years and 6 months at 31 per cent. per annum. (14) Find the simple interest on £926 15s. for 200 days at 7 per cent. per annum. (15) Find the interest on £245 16s. for 73 days at 2 per cent. per annum. (16) Find the simple interest and amount of £417 7s. 9d. for 1 year 10 months at 4 per cent. (17) What is the interest of £535 for 117 days at 4 (18) Find the interest on £800 15s. for 3 years 71 per cent. per cent.? days, at 5 (19) Find the interest on £716 17s. 9d. for 1 year 79 days at 3o per cent. (20) What is the difference between the simple interest of £50 19s. for 7 years at 3 per cent., and that of the same sum for 8 years at 2 per cent. ? (21) £550 10s. was borrowed January 1st, 1861, at the rate of £5 per cent. per annum, what sum repaid the debt on the 20th of October in the same year? (22) Find the simple interest on £639 8s. from May 10th to August 20th, at 5 per cent. per annum. (23) Find the interest on £2755 15s. for 3 years 110 days at £3 2s. 6d. per cent. (24) Find the simple interest on £10,400 at 4 per cent. per annum for 4 years 16 weeks, reckoning 52 weeks to a year. (25) Find the simple interest on £880 for 5 per cent. per annum. months at 7 (26) Find the simple interest and amount of £1277 10s., from the 31st of March till the 4th of July of the same year, at 8 per cent. per annum. (27) Find the interest on £286 from the 1st of June to the 15th of September, at 3 per cent. per annum. (28) What is the interest of £100, for 27 weeks 3 days at 5 per cent. ? (29) What is the amount of £297 15s. 6d. for 12 weeks 4 days at 3 per cent. ? (30) If I am entitled to of the interest on £750 from March 3 to July 27 at 5 per cent. per annum, how much should I receive? In questions of Interest, four things have to be considered, Principal, Rate per cent., Time, Interest. (The Amount is simply the Principal and Interest added together.) If any three of these be given, it is possible to find the fourth. Thus, we have already shown how the Interest (or Amount) may be found when the Principal, Rate, and Time are given. We now proceed to give examples showing how the Principal, Rate, or Time may be found. (1) What amount of capital would be required in order to gain £12 Is. od. in 2 years 5 months, at 3 per cent. ? Here it is required to find the Principal; Time being given. Interest, Rate, and The question now stands thus :-If £100 gain £8 9s. 2d., how much would gain £12 1s. ofd. in the same time? This is evidently a Rule of Three sum, and— £ s. d. £ S. d. £ £ S. 8 9 2 : 12 I 0 :: 100 : 142 10 The capital required is therefore £142 10s. (2) What sum of money will amount to £256 10s. in 4 years, at 3 per cent. simple interest? Here it is required to find the Principal; Amount, Rate, and Time being given. Now, £100 would gain in 1 year £3 10s. £100 in 4 years will amount to £114. The question now stands thus :-If £100 amounts to £114, how much will amount to £256 10s. in the same time? This is evidently a Rule of Three sum, and— 114 : 256 10 :: 100 : 225. The sum of money, or Principal, is therefore £225. (3) At what rate per cent. (simple interest) will £250 amount to £300 12s. 6d. in 4 years? Now, at I per cent. £100 in 1 year gains £1 The question now stands thus :- If at one per cent. a sum of money gains £11 5s., at what rate per cent. will it gain £50 12s. 6d. ? II 5 : 50 12 6 The Rate per cent. is therefore 4. (4) Find the time in which the (simple) interest on £750 10s. will amount to £712 19s. 6d., at 4 per cent. In 1 year interest on £750 10s. at 4 per cent.=£35 12s. 117d. The question now stands thus :—If in 1 year the interest on £750 10s. amounts to £35 12s. 11d., in what time will it amount to £712 19s. 6d.? Therefore, by Rule of Three,— (Note.-The following examples are all taken from Government Examination Papers.) (1) At what rate per cent. (simple interest) will £250 amount to £300 12s. 6d. in 41⁄2 years? (2) What sum must be laid out at 3 per cent. simple interest to amount to £980 10s. 6d. in 4 years? (3) At what rate per cent. (simple interest) will £1016 amount to £1250 in 5 years 5 months? (4) If £880 amount to £899 5s. at simple interest for of a year, what must be the rate per cent. per annum? (5) In what time will £225 amount to £256 10s. at 3 per cent. per annum, simple interest? (6) At what rate per cent. simple interest will £936 13s. 4d. amount to £1157 7s. 4 d. in 4 years? (7) In what time will £225 amount to £256 10s. at 1 per cent. per annum ? (8) What sum will amount to £105 6s. old. in 3 years at 44 per cent. per annum simple interest? (9) In what time will £91 13s. 4d. amount to £105 6s. old. at 4 per cent per annum? |