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13. A merchant bought 40 bushels of grass seed, at the rate of 4 bushels for $6, and sold it at the rate of 5 bushels for $8; what was his whole gain, and what his gain per cent.?

14. A drover bought 20 sheep for $50, and sold them so as to gain 20 per cent.; how much did he receive a head for them?

15. A man bought 60 cords of wood for $200, and sold it at a loss of 5 per cent.; at what price did he sell it per cord?

16. If I buy rice at 4 cents a pound, and sell it at 5 cents, what is my gain per cent.?

17. Sold a cow at auction for $18 that cost $20; what was the loss per cent.?

18. A boy bought peaches at the rate of 3 for 2 cents, and sold them at the rate of 9 for 7 cents; what was his gain per cent.?

19. A tailor sold two coats for $26 each; on one he gained 30 per cent., and on the other he lost 30 per cent.; did he gain or lose on both, and how much?

20. A music dealer sold a piano-forte for $230, which was 8 per cent. less than its value; had he sold it for $300, what would have been his gain per cent.?

21. Two men buy a lot of pork together; A furnishes $200, and B $150; their profits are $70; what is their gain per cent., and what is each one's share of the gain?

22. If a ton of hay is bought for of the market price, and sold for 5 per cent. more than the market price, what per cent. is gained ?

23. A person engaged in speculation sold out his interest for $2100, which was 30 per cent. less than twice as much money as he began with; how much did he begin with, and what was his gain?

86. INTEREST is a sum paid for the use of borrowed money, or on demands after they become due.

The PRINCIPAL is the money lent, or the sum for which interest is paid.

The AMOUNT is the sum of the principal and interest. The RATE PER CENT. is the sum paid for the use of $100 or 100 cents for one year. Thus, if $6 be paid for the use of $100 one year, the rate is 6 per cent. per

annum,

The interest on any sum for one year is always a certain number of hundredths of the principal. Thus, the interest of any sum for one year, at 5 per cent., is 5 hundredths (T) or 2 of the principal; at 8 per cent. it is 8 hundredths (1) or of the principal.

Practically, 30 days are considered a month, and 12 months a year, in computing interest. When no time is named, one year is always understood.

The rate of interest is established by law; and taking more than such rates is termed usury.

1. What is the yearly interest of $80, at 5 per cent. ? ANALYSIS. Since the interest is 5 per cent., or Tår, equal to of the principal, the interest of $80 is zo of $80, or $4. Therefore, &c.

Or thus: Since the interest of $1, or 100 cents, is 5 cents for one year, the interest of $80 is 80 times 5 cents, or 400 cents, equal to $4.*

2. What is the yearly interest of $200, at 6 per cent.?

3. What is the yearly interest of $125, at 4 per cent.?

4. What is the annual interest of $60, at 7 per cent.?

5. What is the annual interest of $95, at 5 per cent.?

• The fractional method is considered preferable in mental exercises.

6. What is the annual interest of $26, at 10 per cent.?

7. What is the annual interest of $228, at 12 per cent.?

8. What is the annual interest of $96.32, at 61

per cent.?

9. What is the annual interest of $144.60, at 8

per cent.?

10. What is the annual interest of $400, at 15

per cent.?

11. What is the annual interest of $500, at 7

per cent.?

12. What is the annual interest of $120.80, at 7

per cent.?

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13. What is the annual interest of $1000, at 9 per cent.?

14. What is the annual interest of $150, at 3 per cent.?

87. 1. What is the interest of $150 for 3 years, at 8 per cent.?

ANALYSIS. Since the interest for 1 year at 8 per cent. is Too, equal to 5, of the principal, for 3 years it is 3 times 25, or 25, of the principal. 25 of $150 is $6, and 25 of $150 is 6 times $6, or $36. Therefore, &c.

Or thus: Since the interest of $150 for 1 year at 8 per cent. is $12, (86,) for 3 years it is 3 times $12, or $36.

2. What is the interest of $30 for 2 years, at 5 per cent.?

3. What is the interest of $50 for 4 years, at 6

per cent.?

4. What is the interest of $90 for 5 years, at 7

per cent.?

5. What is the interest of $75 for 3 years, at 12

per cent.?

6. What is the interest of $64.96 for 2 years, at 64 per cent.?

7. A's note of $25 has been due 2 years; what is the interest, at 6 per cent.?

8. Borrowed $300 for 3 years, at 7 per cent.; what will be the interest ?

9. What is the interest on a note of $46.50, for 5 years, at 10 per cent. ?

10. I owe two notes, one for $145, due in 2 years, at 5 per cent., and the other for $200, due in 3 years, at 6 per cent.; what will be the sum of the interest that I must pay?

11. What is the interest of $225 for 2 years, at 7 per cent.?

12. What is the interest of $50 for 8 years, at 6 per cent. ?

13. What is the interest of $400 for 2 years, at 5 per cent.?

14. Gave a note for $88.96, due in 3 years, at 61 per cent; what will be the interest ?

15. Gave a note due at date, for $45.50, but did not pay it until the end of 5 years; what was the interest due, at 8 per cent. ?

88. 1. At 8 per cent., what part of $1 equals the use of it for 3 years 9 months?

ANALYSIS. Since there are 12 months in 1 year, 9 months is, or of 1 year, and 3 years 9 months are equal to 34, or years. Since the interest of $1 for 1 year at equal to 25 of the principal, for 3 years times, or 4, of, equal to of the Therefore, &c.

8 per cent. is τo,

9 months, it is 3

principal, or $.

2. At 6 per cent., what part of $1 equals the use of it for 2 years 8 months?

3. At 5 per cent., what part of any sum equals the use of it for 2 years 6 months?

4. At 7 per cent., what part of any sum equals the interest of it for 1 year 8 months?

5. What part of any sum equals the interest of it

for 3 years 2 months, at 4 per cent.?

6. What part of any sum equals the interest of it

for 5 years 4 months, at 9 per cent. ?

7. At 64 per cent., for 3 years 4 months, what part of the principal equals the interest ?

8. At 8 per cent., for 5 years 5 months, what part of the principal equals the interest?

9. At 7 per cent., for 2 years 11 months, what part of the principal equals the interest?

10. At 6 per cent., for 2 years 1 month, what part of the principal equals the interest ?

11. At 10 per cent., for 4 years 10 months, what part of the principal equals the interest?

12. At 8 per cent., for 3 years 3 months and 18 days, what part of the principal equals the interest ?

ANALYSIS. Since 30 days make a month, 18 days are , or of a month; and since 12 months make a year, 1 month is of a year; & of 1 month is of 12, or do of 1 year, and 3 months, equal to, is 18 times, or of a year. Hence the interest of $1 for 3, or 운용 years, at 8 per cent., is Ts of it. (88, Ex. 1.) Therefore, &c.

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13. What part of the principal equals the interest, for 2 years 5 months and 10 days, at 6 per cent.? 14. What part of the principal equals the interest, for 1 year 8 months and 25 days, at 7 per cent.? 15. What part of the principal equals the interest, for 2 years 3 months and 6 days, at 6 per cent.? 16. What part of the principal equals the interest, for 2 years 11 months and 6 days, at 5 per cent. ?

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