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9. If 45 bushels of grain, at 75 cents per bushel, will pay a debt, how many bushels, at 1 dollar per bushel, will pay the same?
cts. cts. bush. As 100 : 75 :: 45 : Ans. 33bu. 3pks.
Questions. i. What does the Rule of Three Di- portion ? rect teach?
1. What does the Rule of Three In2. Of the three given numbers, what verse teach? are the first two ? What is the last ? 2. When more requires more, or less
3. In stating questions in the Rule requires less, to what Rule does the of Three, which two numbers must al- question belong ? ways be of the same name or kind? 3. If more requires less, or less re
4. Of what kind must the middle term quires more, to what Rule does the be ?
question belong? 5. What do four points set in the mid 4. What is the Rule for Inverse prodle of four numbers denote?
portion? 6. What is the Rule for Direct pro
The Latin term per centum, and its abbreviation per cent, signify by the hundred. Thus, 1 per cent of any number is ado of that number; 2 per eent is too ; 3 per cent 180; 4 per cent is too ; 5 per cent is
1. What is 4 per cent of 1156 dollars ? $1156
4 per cent is 16 y ; therefore we multi4 ply by 4 and divide by 100. To divide by
100, we need only cut off two figures from $46,24
the right. Ans. 46 dollars 24 cents. 2. What is 5 per cent or nóg, of $145 68 cents ?
$ cts. mls. 3. What is 12 per cent of $250 ? Ans. 30. 4. What is 7 per cent or to of $500 ? Ans. 35. 5. Find 6 per cent of $96,48.
Ans. 6. Find 9 per cent of $216.
Ans. 19 44. 7. What is 5 per cent of $956, 14 ? Ans. 52 58 710 8. What is 21 per cent of $65,20 ? Ans. 1 46 7.
5 78 8%
Interest is an allowance of so much per cent made by a debtor to a creditor, for the use of money.
In the New England States, the rate of interest is established by law at 6 per cent per annum ; that is, $6 for the use of $100, or £6 for the use of £100, for one year; and in the same proportion for a greater or less sum, or for a longer or shorter time.
In New York, the lawful interest is 7 per cent, &c. 1. Principal is the sum due, for which interest is paid. 2. Rate is the sum per cent agreed on. 3. Amount is the principal and interest added together.
Interest is of two kinds, Simple and Compound.
Simple Interest is when interest is computed only on the original principal. 1. To find the interest of any given sum for one year.
RULE. Multiply the principal by the rate per cent and divide the product by 100; the quotient will be the interest for one year.
Note. By this Rule are calculated Commission, Brokerage, Insurance, buying and selling Stock, &c.
1. What is the interest of $511 for one year, at 6 per cent?
Principal $511 We multiply by the rate per Rate per cent X6 cent, and point off two figures
for dividing by 100, and the anInterest 30,66
swer is 30.10%
66 dollars, or 30 dola
lars 66 cents. 2. What is the interest of $1236, 38 cents for 1 year, at 7 per cent ?
Principal $1236,38 After multiplying by the Rate per cent
X7 rate per cent, we place the
separatrix as in Federal mo
86'54,66 ney. Then to divide by 100 we point off two figures, and the answer is 86 dollars 54196 cents, or $86 54 cents 6-%m.
3. What is the interest of 341 dollars 37 cents for one year, at 5 per cent ? $341,37 After multiplying by the rate per cent 5 and placing the separatrix as in multipli
cation of Federal money, we need only 17'06,85 call the figures on the left so many cents and those on the right decimals of a cent; thus 1706,85 cents=$17 6c. 8 om.
3. Required the interest of $800 for one year, at 5] per cent.
Ans. $44. 4. Required the interest of $956,25 for one year, at 7
Ans. $66 93c. 7 fm. 5. Required the interest of $1356 for one year, at 6 per cent.
Ans. $81,36. 6. What is the interest of £500 for one year, at 5 per cent?
Ans. £25. 7. Required the amount of $1528,25 for one year, at 4
Ans. $1589,38. 2. To calculate interest for any number of years, months, fc.
per cent ?
1. Find the interest for one year as before. 2. Multiply the interest for one year by the given num
ber of years.
3. For the months, take even parts of a year ; thus, for 1 month take is of a year, and for 2 months sa or &: &c.
4. For days, take even parts of a month, allowing it to contain 30 days ; (or, if the sum be large and great accuracy required, work for the days by the Rule of Three Direct, by saying, as 365 days are to the interest for one year, so is the given number of days to the interest re« quired.)
1. What is the interest of $84,54 for 3 years 7 months and 10 days, at 6 per cent per annum ?
6 6 mo.=} of 1 year. $507,24 interest for 1 year in cts.
1521,72 ditto for 3 years. I mo.= of 6 mo. 253,62 ditto for 6 months. 10 days=} of 1 mo. 42,27 ditto for 1 month.
14,09 ditto for 10 days.
(31cts. 7m. Answer 1831,70 = 1831cts. 7m. or $18. 2. What is the interest of 210 dollars for 5 years, at 6 per cent per annum ?
Ans. $63. 3. Required the interest of $511,65 for 3 years and 4 months, at 5 per cent per annum.
Ans, $85,27 4. Of $48,25 for two and a half years, at 6 per cent
Ans. $7, 23c. 7 Bom. 5. Of 249 dollars for 3 years 9 months, at 6 per cent.
Ans. $56, 2} cents. 6. Of $27,56 for 2 years, at 5
Ans. $2 75cts. 6m. 7. Of $951,17 for 4 years, at 5 per cent.
Ans. $190 23cts. 4m. 8. What is the interest of $1 for 16 years 8 months, at 6 per cent per annum ?
Ans. $1. 9. What is the interest of $824,41 for 3 years
5 mos. and 10da., at 6 per cent per annum ? Ans. $170,35cts. 92m.+ 10. What will £1825 amount to in 5 years, at 4
Ans.' £2190. 11. What is the interest of $145,96 for 3 years 9 mos., at 5per cent per annum ?
Ans. $28,73c. 5m. 12. What will $15195 amount to in 5 years 4 months and 20 days, at 7 per cent? Ans. $20926, 89c. 16 m. +
13. What is the interest of $456 from April 15th, 1829, to March 5th, 1833, at 6 per cent ?
Ans. $106,40. 14. A note dated October 5th, 1831, for 256 dols. was paid,
principal and interest, March 20th, 1834: I demand the amount paid. Interest at 6 per cent. Ans. $293,76.
SHORT PRACTICAL RULES FOR CALCULATING INTEREST
WHEN THE RATE IS 6 PER CENT.
1. To find the interest for any number of months at 6 per cent.
In casting the interest of any sum of money for 1 year, or 12 months, at 6 per cent, it is evident that the rate per cent. is just half the number of months in a year, or onehalf per cent per month. Hence, for any term of time at 6 per cent, the rate being just } per cent per month, it is evident that if we multiply the given sum by half the number of months, it will give the interest required.--Hence the following
Multiply the principal by half the number of months, and divide the product by 100; the quotient will be the interest for the given time.
1. What is the interest of $148,21 for 1 year 4 months, or 16 months, at 6 per cent per annum ? Principal $148,21 After placing the separatrix in the Half the months 8 product, we point off the 2 right hand
figures (for dividing by 100.) 11'85,68=$11 85c. 6. m. 2. What is the interest of $225 for 3 years and 4 mos. at 6 per cent per annum ?
Ans. $45,00. 3. What is the interest of $95 34 for 9 months, at 6 per cent?
Ans. $4, 29+. 4. Required the interest of $211,25 for 7 months, at 6
Ans. $7, 39c. 3om.+ 5. Required the interest of $137 for 2 months, at 6 per cent?
Ans. $1,37c. 6. What is the interest of £125 for 8 months, at 6 per