(7) 60 chickens, 30 ducks, 10 turkeys; value £22 10s. (8) 4545 pairs of boots; 9090 pairs of shoes. Boots, 10s. 8d.; (22) 36,000. (23) 40; 45. (26) £9000. (21) Nitre, 152 ton; sulphur, '19 ton; charcoal, 29 ton. (25) 9 weeks. (27) Loss, £1 2s. 1d.; 4 per cent. (28) £80 15s.; A, £16 3s.; B, £24 4s. 6d. ; C, £40 7s. 6d. (29) 5356°26 miles; 15:13 + miles. (30) 14183 ft. 56 (31) A, 12 days; B, 1259 days; C, 8,5 days. (32) 8d. (FEMALES.) INTEREST. Interest is the consideration paid for the use of money lent. The Rate of interest is the consideration paid for the use of a certain sum for a certain time. Interest is usually calculated on the basis of so much per £100 for each year the money is lent; or at the rate of so much per cent. per annum. Thus, if a person borrows money at the rate of £5 for each £100 for each year the loan continues, the interest is said to be at the rate of 5 per cent. per annum. So, "per cent." means, for each £100; 66 "" per annum means, for each year. The money lent is called the Principal. The Principal, together with the interest at the end of any given period, is called the Amount. Thus, if £100 be lent for a year at 5 per cent., the interest at the end of the year would be £5, and the Amount at the end of that time would be £100 +£5 = £195. Interest may be either Simple or Compound. Simple Interest is that which is received only on the original Principal. Compound Interest is that which is received, not only on the original principal, but on the interest which accrues from time to time, and which, being added to the sum originally lent, becomes new Principal. Thus, if £100 be lent for 5 years at Compound Interest, at the end of the first year the interest, £5, is not paid to the lender, but remains in the hands of the borrower, who therefore has to pay interest during the second year on £105. Similarly, during the third year he has to pay interest on £105 + interest on £105 for one year, and so on till the end of the five years. Thus, in Simple Interest the Principal always remains the same, but in Compound Interest the Principal is increased at the end of any given period by the Interest due for that given period. SIMPLE INTEREST. To find the Interest of a given sum of money at a given rate per cent., for a given number of years. Rule.-Multiply the Principal by the rate per cent., divide the product by 100, and multiply the result by the number of years. (1) Find the Interest on £300 for 3 years at 4 per cent. £100 Here, Interest on £100 for 1 year at 1 per cent.=1= 100 The reason of the rule will appear from the above example. (2) Find the Interest on £925 16s. 8d. at 7 per cent. for 5 Following the rule, we divide by 100 (cutting multiply this by the rate per cent. (7) and off two figures to the right in each line). We thus get the Interest for one year, viz., £64 16s. 2d.; then, multiplying by 5, we obtain the Interest for 5 years. Note. It is sometimes convenient to multiply by both the rate per cent. and the number of years before dividing by 100. If the Amount were required in Example 2, it would be found by adding the Principal to the Interest, thus : £925 16s. 8d. + £356 8s. 11d. = £1282 5s. 7d. (3) Find the Interest and Amount of £1284 15s. 10d. at 2 per cent. for 3 yr. 5 m. (4) What will £1126 amount to in 4 years 17 weeks, at 5 per cent. ? (5) Find the Interest of £173 155. 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. 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 (3) Find the interest on £1061 years. per cent. for 6 years. 15s. at 23 per cent. for 5 |