EXAMPLES. What is the interest of £420 for 1 year, at 7 pr. cent, pr. annum. Ans. £29 88. 3. What is the interest of £800, for 1 year, at 7 pr. cent, pr. annum ? Ans. £56 4. What is the interest of £76, for 1 year, at 5 pr. cent? 5. Whst is the interest of £211 5s. for 6. What is the interest of £472 pr. annum? 7. What is the interest of £270 cent, pr. annum? 18. for 10s. 8. What is the interest of $ 542, for annum ? 9. What is the interest of $ 800, for Ans. 3 168. 1 year, at 7 pr. cent? Ans. 14 15s. 9d. 1 year, at 7 pr. cent, Ans. £33 Os. 10d. 6d. for 1 year, at 5 pr. Ans. 13 10s, 6zd. 1 year, at 7 pr. cent, pr. Ans. 37 94cts. one year, at 6 pr. cent? Ans. 48 00 10. What is the interest of 875 35cents, for one year, at 6 pr. cent? Ans. 52 52 11. What is the amount of a bond for $387 50 cents, for one year, at 6 pr. cent? Ans. 410 75cts. Note 1. When the principal consists of dollars, multiply by the rate pr.'cent; the product will be the interest for 1 year, in cents. Note 2. When the amount is required, add the principal to the interest. CASE II. 1. If the interest required be for years, months, and days, take the number of months, and set it under the place of tens, take part of the number of days and put it under the place of units for a multiplier. 2. For the odd days, (if any) see what proportion, they bear to the week, and divide the principal by this proportion, and then proceed to multiply as in whole numbers; the product will be the interest for the whole time, in dollars, cents, and mills. EXAMPLES. Required the interest of 10 44cts. for 3 years 5 months and 10 days, at 6 pr. cent, pr. annum. 2. What will 780 dols. amount to, at 6 pr. cent, in 5 years 7 months and 12 days? Ans. 975 99 cts. 3. What is the interest of $824 15 cts. for 22 weeks, at 7 pr. cent? Ans. 24 40 cts. 7 m. 4. What is the interest of $ 438 24 for 4 years 9 months and 14 days, at 7 pr. cent? Ans. 146 90cts. 7m. CASE III. When there is a fraction as 4, &c. in the rate pr. cent. RULE. Multiply the principal by the rate pr. cent. to the product add &c. of said principal, and divide by 100 for the interest rc> quired. EXAMPLES. 1. What is the interest of $428 for one year, at 62 pr. cent, fr. annum? Ans. 11. 178. 1 2. What is the interest of 2167. 58. for one year, at 5 pr. cent? 3. What is the interest of $ 300 for one year, at 64 pr. cent, pr. annum? Ans. 18 75 cts. CASE IV. To find the interest of any sum of money, for any number of years and parts of a year. 1. Find the interest for 1 year, and multiply this by the given number of years. 2. If there be months and days, work for the months, by the aliquot parts of a year, and for the days, by simple proportion. EXAMPLES. 1. What is the interest of 64 dois. 58 cts. for 3 years 5 months and 10 days, at 5 pr. cent? Ans. 11 12 cts. 1m. 4 mo. 1 mo.= 64 58 5 32290 Interest for one year in cents. 3 96870 for 3 years. 2690 for 1 month. Ans. 11,12,19 1112 cts. or $ 11,12 c. 1m. 2. What is the interest of g 325 41 cts. for 3 years, and 4 months, at 5 pr. cent? Ans. $54 23 cts. 5 m. 6 3. What will 3000l. amount to in 12 years and 10 months, at pr. cent? Ans. 5310/. 4. What will $730 amount to at 6 pr. cent, in 5 years months and 12 days? Ans. $975 99 cts. INSURANCE, COMMISSION, AND BROKERAGE. Are allowances to Insurers, Factors, and Brokers, at a stipulated rate pr. cent, as a premium for their services. The same rules used in simple interest, apply to each of these cases. 1. What is the commission on £287 10 s. at 3 pr. cent? Ans. 10 1 s. 3 d. 2. A Broker sells goods for me to the amount of £2575 17 s. 6 d. what is the brokerage at 4 s. pr. cent? Ans. £5 3 s. 04. 3. What is the insurance of a house, valued at $1853, at 75 cts. pr. cent? Ans. 13 89 cts. DISCOUNT. DISCOUNT is an allowance made for the payment of any sum of money before it becomes due; and is the difference between that sum due some time hence, and its present worth. The present worth of any sum, or debt, due some time hence, is such a sum, as, if put to interest, would in that time and at that rate pr. cent, for which the discount is to be made, amount to the sum, or debt then due. What remains after the discount is deducted, is the present worth. RULE. As the amount of 100%. or 100 dols. at the given rate and time: is to the interest of 100 at the same rate and time, so is the given sum to the discount. Subtract the discount from the whole debt, and the remainder will be the present worth. Or; as the amount of 100, is to 100, so is the given sum to the present worth. PROOF. Find the amount of the present worth for the time and rate proposed, which must equal the given sum, or debt. EXAMPLE. What must be discounted for the ready payment of 100 dols. due a year hence, at 6 pr. cent pr. annum ? As 106 6 :: 100: 5 66 Ans. 100,00 years sum. 5,66 discount. $94,34 the present worth. 2. What sum in ready money, will discharge a debt of £925, due 1 year and 8 months hence, at 6 pr. cent? As 110: 100 :: 925 : 840 18 2 Ans. 3. What is the present worth of 600 dols. due 4 years hence, at 5 pr. cent? Ans. $500 4. *What is the present worth of £100, one quarter due in 3 months, and the remaining 3 quarters, in 5 months, discount 7 pr. cent? Ans. 97 8 s. 10 d. + 5. What is the difference between the interest of $1204, at 5 pr. cent pr. annum, for 8 years, and the discount of the same, for the same time and rate? Ans. 137 60 cts. EQUATION OF PAYMENTS: Is finding the equated time, to pay at once, several debts due at different times, so that no loss shall be sustained by either party. RULE. Multiply each payment by its time, add the several products together, and divide the sum by the whole debt; the quotient. will be the answer. PROOF. The interest of the sum, payable at the equated time, will equal the interest of the several payments. EXAMPLES. 1. A owes B. $ 380, to be paid as follows, viz. 100 in six months, 120 in 7 months, and 160 in 10 months; What is the équated time for the payment of the whole debt ? 100 X 6 = 600 120 X 7= 840 160 X 10 = 1600 380 )3040(8 months. Ans. 3. The firm of B. & C. owe to the firm of B. & Co. the sum of 300; payments as follows: 100 in 3 months, 100 in 4 months, and 100 in 6 months; required the equated time for the payment of the whole debt? Ans. 4 months. Note. When Sundry sums are to be paid at different times, find the rebate, or present worth of each payment separately, then add them into one sum. |