PART II. INTEREST. 240. Interest is compensation for the use of money. 241. The money for which interest is paid is called the principal. 242. The principal and interest together are called the amount. NOTE.-Interest is usually reckoned in per cent, the principal being the base; that is, the borrower pays for the use of money a sum equal to a certain per cent of the principal. "The rate of interest" is the per cent per annum which the borrower agrees to pay. When a man loans money "at 6%" he expects to receive back the principal, and a sum equal to 6% of the principal for every wear the money is loaned and at that rate for fractions of years. EXAMPLE. Find the interest of $257 for two years at 6 %. Operation. $2'57 .12 5.14 25.7 $30.84 Explanation. The interest of any sum for 2 years at 6% is 12 hundredths of the principal. One hundredth of $257 is $2.57, and 12 hundredths of $257 is 12 times $257 or $30.84. 1. Find the interest of $242 for 3 yr. at 7 %. (a) Find the sum of the six results. EXAMPLE. Find the interest of $324.50 for 2 yr. 5 mo. at 6 1. Find the interest of $325.40 for 1 yr. 6 mo. at 7 2. Find the interest of $420.38 for 2 yr. 10 mo. at 3. Find the interest of $221.60 for 2 yr. 3 mo. at 6% 4. Find the interest of $145.20 for 1 yr. 9 mo. at 5 5. Find the interest of $340.10 for 3 yr. 1 mo. at 4 (a) Find the sum of the five results. * In an interest problem, if there is a fraction of a cent in the answer an action is not greater than 2, it may be disregarded; if it is more than 1, re 1 cent. Interest. 244. TO COMPUTE INTEREST FOR ANY NUMBER OF YEARS, MONTHS AND DAYS. NOTE.-In computing interest, 30 days is usually regarded as 1 month, and 360 days as 1 year; so each day is of a month or a year. EXAMPLE. of Find the interest of $256.20 for 2 yr. 7 mo. 13 days at 6 %. OPERATION AND EXPLANATION No. 1. 1. Find the interest of $350.40 for 2 yr. 5 mo. 7 da. at 6 %. 2. Find the interest of $145.30 for 1 yr. 7 mo. 10 da. at 8 %. 3. Find the interest of $174.20 for 2 yr. 3 mo. 15 da. at 7 %. 4. Find the interest of $253.40 for 3 yr. 6 mo. 20 da. at 5 %. (a) Find the sum of the four results. 245. THE" six-per-cent method." NOTE. If the teacher so prefers, the problems on the three preceding pages, as well as those that follow, may be solved by the "six per cent method." Find the interest of $243.25 for 2 yr. 5 mo. 18 da. at 6%. (3) How find the interest at 8% ? at 9%? at 4% ? at 3% ? Interest. 246. PROBLEMS TO BE SOLVED BY THE "SIX PER CENT METHOD." 13 da. at 6 %.* 1. Find the interest of $265 for 1 yr. 3 mo. 2. Find the interest of $346 for 2 yr. 5 mo. 20 da. at 6 %.† 3. Find the interest of $537 for 1 yr. 7 mo. 10 da. at 6 %.‡ 4. Find the interest of $428 for 3 yr. 3 mo. 14 da. at 6%. 5. Find the interest of $150 for 1 yr. 6 mo. 15 da. at 6 %. (a) Find the sum of the five results. 6. Find the interest of $245.30 for 6 mo. 18 da. at 7 %. § 7. Find the interest of $136.25 for 8 mo. 10 da. at 7 %. 8. Find the interest of $321.42 for 5 mo. 15 da. at 7 %. 9. Find the interest of $108.00 for 10 mo. 8 da, at 7 %. 10. Find the interest of $210.80 for 7 mo. 21 da. at 7 %. (b) Find the sum of the five results. 11. Find the amount of $56.25 for 2 yr. 4 mo. 2 da. at 6 %. 12. Find the amount of $31.48 for 1 yr. 5 mo. 11 da. at 6 %. 13. Find the amount of $55.36 for 2 yr. 8 mo. 12 da. at 6 %. 14. Find the amount of $82.75 for 2 yr. 10 mo. 8 da, at 6 %. 15. Find the amount of $27.35 for 1 yr. 1 mo. 1 da. at 6%. (c) Find the sum of the five results. 16. Find the amount of $875 for 3 yr. 8 mo. 15 da. at 5 %. 17. Find the amount of $346 for 2 yr. 6 mo. 12 da. at 4 %. 18. Find the amount of $500 for 1 yr. 7 mo. 18 da. at 3%. 19. Find the amount of $600 for 2 yr. 5 mo. 21 da. at 8 %. 20. Find the amount of $825 for 1 yr. 9 mo. 24 da. at 9 %. (d) Find the sum of the five results. § First find the interest at 6%; then add of that sum to itself. |