12. What is the interest of $64.16 for 124 mo. ? Solution. — 6 mo. 20 da. = 6 mo. = 1 of 20 mo. Hence, the required interest must equal f of it of the principal, or of $2.547, which is $.849. 25. What is the interest of $57.84 for 20 mo.? 42. What is the interest of $83.60 for 10 mo.? (d.) Interest for any time wbatever can usually be computed easily by dividing the time into some of the above convenient parts, as illustrated in the following solutions. Note. - In these solutions, letters are used to mark the numbers and indicate to the eye how they have been obtained. Thus, in the first solotion, “.04 of a = b = $17.895” means that $17.895 is .04 of $447.38. 46. What is the interest of $447.38 for 8 mo. 10 da. ? 47. What is the interest of $57.20 for 7 mo. 15 da. ? 59. What is the amount of $697 for 6 mo. 26 da.? 111. To compute the Time. (a.) To compute the time during which money has been on interest, i. e. the time between the dates on which interest began and ended, first reckon the number of entire years, then the number of entire calendar months remaining, and then the remaining days. Note.-This method, although different from that usually given in school arithmetics, is the one adopted by banks and business men, except when the interest is to be computed for some number of days, as 60 days, 90 days, etc., when they count the days from one date to the other. 1. What is the time from April 13, 1853, to Nov. 21, 1856 ? Solution.— From April 13, 1853, to April 13, 1856, is 3 years ; from April 13 to Nov. 13 is 7 months; and from Nov. 13 to Nov. 21 is 8 days. Hence, the time is 3 yr. 7 mo. 8 da. 2. What is the time from June 23, 1854, to April 8, 1857? SOLUTION.-From June 23, 1854, to June 23, 1856, is 2 yr.; from June 23, 1856, to March 23, 1857, is 9 months; from March 23 to Mareh 31 (the last day of March) is 8 days, to which adding the 8 days in April gives 16 days. Hence, the time is 2 yr. 9 mo. 16 da. 3. What is the time from Oet. 30, 1855, to March 17, 1857 ? Solution.—From Oct. 30, 1855, to Oct. 30, 1856, is 1 year; from Oct. 30, 1856, 'to Feb. 28, 1857 (the last day of February), is 4 months. There are no days left in February, but there are 17 in March. Hence, the time is 1 yr. 4 mo. 17 da. 4. What is the time from Aug. 18, 1853, to March 12, 1856 2 Solution. From Aug. 18, 1853, to Aug. 18, 1855, is 2 years; from Aug. 18, 1855, to Feb. 18, 1856, is 6 mo.; from Feb. 18, 1856, to Feb. 29, 1856 (February having 29 days in leap-year), is 11 days, to which adding the 12 days in March gives 23 days. Hence, the time is 2 yr. 6 mo. 23 da. . 5. What is the time from April 5, 1847, to June 12, 1857? 6. What is the time from Aug. 3, 1850, to June 27, 1855 ? 7. What is the time from May 23, 1848, to Sept. 11, 1852 ? 8. What is the time from Dec. 21, 1853, to March 6, 1857 ? 9. What is the time from Jan. 20, 1855, to March 19, 1856 ? 10. What is the time from Jan. 20, 1855, to March 20, 1856 ? (b.) What is the interest of 11. $1000 from Feb. 13, 1852, to June 9, 1856 ? 12. $628.13 from Nov. 8, 1850, to Dec. 3, 1852? 13. $358.36 from June 20, 1856, to June 13, 1857 ? 14. $924.53 from Oct. 31, 1850, to March 13, 1853 ? 27. Aug. 3, 1847, I borrowed $450; and, Nov. 23, 1847, I borrowed $683.50 more. Jan. 1, 1848, I paid both debts with interest. What was their amount? 28. April 27, 1852, I bought 7 acres of land at $128.36 per acre; Nov. 18, 1852, I sold it at $150.73 per acre. If money was worth 6 per cent per year, how much did I gain by the transaction ? 29. Oct. 5, 1857, I bought a lot of grain for $619.27; Nov. 3, I sold a part of it for $328.13; and, Nov. 7, I sold the remainder for $250. Money being worth 6 per cent interest, how much did I lose by the transaction ? 112. Interest at various Rates (a.) We may find the interest when the rate is other than 6 per cent, by first computing the interest at 6 per cent, and then getting such part of this as the given rate is of 6 per cent. ILLUSTRATIONS.— Interest at 9 per cent. = = = 11 times the interest at 6 per cent; interest at 74 per cent. = = * = 11 times the interest at 6 per cent, etc. |