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12. What is the interest of $1.00 at 12 per cent. per annum for 1y. 3d.? 1 m. 3 d.? 2 m. 3 d.? 3 m. 3 d.? 4 m. 3 d.? Ans. $0.121; $0.011; $0.021; $0.031; $0.041

105. To find the interest of any principal, at 12 per cent. per annum, for any given time.

EXAMPLES.

1. What is the interest of $500 at 12 per cent. per annum for 1 y. 3 m. 3 d.? 2 y. 5 m. 6 d.? 1 y. 4 m. 9 d.?

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(2) REASONING.-Since the interest of $1.00 at 12 per cent. per annum for 1 y. 3 m. 3 d. is 151 mills, the interest of $500 is as many mills as are represented by the product of 500 multiplied by 151, which is 85500.

(3) RESULT.-Hence, the interest, etc. (repeat the problem) is $85.50

RULE.

Multiply the principal by the interest of $1.00 at 12 per cent. per annum for the given time.

REMARK 1.-Of course, in this multiplication both multiplicand and multiplier must be considered as abstract numbers. The decimal point in the product must be placed as in 102. (See 37, ex. 43. REMARK.)

REMARK 2.-The interest of any sum of money at 6 per cent. per annum for any given time is one half that at 12 per

The interest at 5 per cent. is
The interest at 7 per cent. is
The interest at 8 per cent. is
The interest at 10 per cent. is

that at 12 per cent.

that at 12 per cent. that at 12 per cent. that at 12 per cent.

cent.

PERCENTAGE.

2. What is the interest of $125 for 1 y. 2 m. 9 d. at 6 annum? Ans. $8.933

per

cent. per

3. What is the interest of $150 for 1 y. 1 m. 12 d. at annum?

6 per

Ans. $10.05 cent. per 4. What is the interest of $175 for 7 m. 15 d. at 6 per cent. per annum?

Ans. $6.561

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$8.933

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5. What is the interest of $500 for 1 y. 2 m. 18 d. at

6 per cent. per annum?

Ans. $36.50

6. What is the interest of $60 for 1 y. 1 m. 24 d. at 6

Ans. $4.14

per cent. per annum?
7. What is the interest of $75 for 11 m. 6 d. at 6
cent. per annum?

per

Ans. $4.20

8. What is the interest of $420 for 7 m. 24 d. at 6 per cent. per annum?

6

Ans. $16.38

9. What is the interest of $120 for 3 y. 6 m. 12 d. at per cent. per annum?

Ans. $25.44

10. What is the interest of $125 for 6 months at 6 per cent. per annum?

Ans. $3.75 11. What is the interest of $150 for 1 month at 6 per cent. per annum? 2 months? 3 months? 4 months? etc., to 11 months? Ans. $0.75, etc. 12. What is the interest of $500 for 1 year at 6 per Ans. $30.00 cent. per annum? 2 y.? etc., to 25 y.? 13. What is the interest of $77.40 for 1 y. 2 m. 6 d.

per

annum?

at 6 Ans. $5.50 per cent. 14. What is the interest of $200 for 1 y. 6 m. at 6 per

cent. per annum?

Ans. $18.00

15. What is the interest of $800 for 1 y. 3 m. at 6 p cent. per annum?

Ans. $60.00

per

16. What is the interest of $250 for 2 y, 15 d. at 6 per cent. per annum? Ans. $30.621

17. What is the interest of $120 for 1 y. 2 m. at 6 per cent. per annum? Ans. $8.40 18. What is the interest of $150 for 2 y. 6 m. at 6 per cent. per annum? Ans. $22.50 19. What is the interest of $1000 for 3 months at 6 per cent. per annum? 4 m.? 5 m? 8 m.? 9 m? 1y.? 1y. 1 m.? 1 y. 3 m.? 1 y. 7 m.? 1 y. 8 m. 6 d.? 2y. 5 m. 9 d.? 2 y. 11 m. 29 d.? Ans. $15; $20, etc.

20. What is the interest of $3120 for 1 y.

at 6

per cent. per annum?

3 m. 24 d. Ans. $246.48

21. What is the interest of $200 from March 14, 1867, to July 14, 1875, at 6 per cent. per annum?

Ans. $100.00 22. What is the interest of $700 from August 15, 1867, to October 17, 1870, at 6 per cent. per annum?

Ans. $133.231

23. What is the interest of $400 for 1 y. 3 m. at 6 per cent. per annum? 10 per cent.? Last Ans. $50.00 24. What is the interest of $750 for 1 y. 6 m. 15 d. at 5 per cent. per annum? 6 per cent.? 7 per cent.? 8 per cent.? 10 per cent.? Ans. $57.811, etc.

25. What is the interest of $375 for 20 years at 5 per cent. per annum? 16 y. 4 m. at 6 per cent. per annum? 14 y. 33 m. at 7 per cent. per annum? 12 y. 6 m. at 8 per cent. per annum? 10 years at 10 per cent. per Ans. $375. REMARK.—Any sum of money will double itself at simple interest in as many years as are represented by the quotient of 100 divided by the RATE per cent.

annum?

per cent. per annum?

26. What is the amount of $125 for 2 y. 6 m. 9 d. at 6 Ans. $143.94 27. What is the interest of $10.00 for 2 months at 6 per cent. per annum? $11.00? $12.00? $13.00? $14.00? $15.00? $25.00? Ans. $0.10; $0.11, etc. 28. What is the interest of $125 for 60 days at 6 per cent. per annum? $150? $175? $200? $225? $262? Ans. $1.50; $1.75, etc.

REMARK.-Hence, the interest of ANY SUM of money for 60 days, at 6 per cent. per annum, is found by removing the decimal point in the given sum TWO PLACES to the left.

29. What is the interest of $1.00 for 60 days at 6 per cent. per annum? $2.00? $3.00? $4.00? $5.00? $1.25? $2.50? Ans. $0.01, etc., to $0.025 30. What is the interest of $100 for 60 days at 6 per cent. per annum? $110? $120? $125? $140? $1000? $1250? $5275? Ans. $1.10, etc., to $52.75 31. What is the interest of $125 for 63 days at 6 per cent. per annum? $180? $300? $350?

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(2) REASONING -Since the interest for 60 days is $1.25, the interest for 3 days is (that for 60 days) 6 cts.

(3) RESULT.-Hence, the interest for 63 days is $1.31

32. What is the interest of $120 for 93 days at 6 per annum? $130? $140? $150?

cent.

per

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(2) REASONING.-Since the interest for 60 days is $1.20, the interest for 30 days is ( that for 60 days) 60 cts.; and since the interest for 30 days is 60 cts., the interest for 3 days is ( that for 30 days) 6 cts.

(3) RESULT.-Hence, the interest for 93 days is $1.86. REMARK. Examples 31 and 32 illustrate a very quick method of calculating the BANK Discount on any sum of money, since Banks usually discount for 30, 60, or 90 days, charging interest for 2 additional days, called DAYS OF GRACE on the last of which the borrower must pay his NOTE.

33. What is the interest of $500 for 33 days at 6 per cent. per annum? $600? $700? $800? Ans. $2.75, etc.

PROBLEMS IN REVIEW.

NUMERATION.

1. Express 60005001 in words.

2. Express 90800700060005403021000 in words. 3. Express .000121; .01010101; .0453 in words. 4. Express .1; .10; .01; .100; .005; 5000 in words. 5. Express ; ; ; ; ; 17 in words, and state 7 1; the full meaning of each fraction.

5

13 261

25

6. Express 32; 7; 5; 6; 18 in words, and state the exact meaning of each mixed number.

7. Express .11; .33; .07§; .00012,7, in words, and explain the meaning of each mixed fraction.

8. What is meant by 4.03; apples?

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