84. The loss 40% of his cost.

on the sale of a horse was $50, which was What was his cost?

REVIEW QUESTIONS.

What is meant by per cent? By rate per cent? In what way may per cent be expressed? Explain the use and non-use of the decimal point in writing rate per cent? Define base. Define percentage. To what term in multiplication does each term in percentage correspond? How may each term be found? Which terms in percentage are factors? State and explain Case I. Case II. Case III. To which term in percentage does the cost of an article correspond? The gain or loss? Define premium.

INTEREST.

236. Interest is the compensation or payment due one party (the lender) from another party (the borrower) for the use of money.

237. The Principal is the sum of money for whose use a compensation is made.

238.

The Rate of Interest is a certain rate per cent, which the interest is of the principal, for a specified time, usually one year.

239. interest.

The Amount is the sum of the principal and

ORAL.

1. What is the interest of $100 for 1 year, at 6%? SOLUTION. The interest is 6% of $100, that is, $6.

2. What is the interest of $40 for 3 years, at 10%?

SOLUTION I.-The interest of $40 for one year, at 10% interest, is $4; for 3 years it is 3 times $4, that is, $12.

SOLUTION II.-The interest of $1 at 10% for one year is 10 cents; for three years it is 30 cents. The interest on $40 for 3 years, at 10%, is 40 times 30 cents, that is, $12.

SOLUTION. The interest of $30 for 1 year at 9% is $2.70; for 4 mos. († of a year) the interest is † of $2.70, or 90 cents.

$2.70+.90 $3.60.

20. What is the interest of $60 for 1 yr. 3 mos. at 6%? 21. What is the interest of $400 for 2 yrs. 6 mos. at 10%? 22. What is the interest of $900 for 3 yrs. 2 mos. at 6%? 23. What is the interest of $150 for 1 yr. 9 mos. at 6%? 24. What is the interest of $80 for 4 yrs. 4 mos. at 8%? 25. What is the interest of $600 for 5 mos. at 8%?

SUGGESTION.- Find interest for 1 year, then for 1 month, then for 5 months.

26. Find interest of $120 for 7 mos. at 4%.

27. Find interest of $360 for 11 mos. at 9%.

WRITTEN.

28. Find interest of $240 for 3 years 7 months at 8%.

PROCESS.

12

$240

.08

43

$68.80

SOLUTION I.-Interest for 1 year=$240.08= $19.20. Interest for 3 yrs.-$19.20×3=$68.80. SOLUTION II-Express, in form for cancellation, the interest for 1 year, $240.08.

Express the division of this product by 12, which is the interest for 1 month. Express the multiplication of this quotient by 43, the number of months (3 yrs. +7 mos.-43 mos.).

By cancellation, the result is $68.80.

29. Find interest of $360 for 2 yrs. 5 mos. at 6%.
30. Find interest of $600 for 3 yrs. 11 mos. at 8%.
31. Find interest of $720 for 1 yr. 9 mos. at 8%.
32. Find interest of $480 for 3 yrs.
6 mos. at 10%.
33. Find interest of $90 for 4 yrs. 5 mos. at 6%.
34. Find interest of $72 for 5 yrs. 3 mos. at 8%.
35. Find interest of $418 for 18 days at 6%.

PROCESS.

12 $480

30

.06

18

$1.44

SOLUTION.-Express, in form for cancellation,
the interest for 1 year, $480X.06.

Express the division of this product by 12, which
result is the interest for 1 month.

Express the division of this quotient by 30, which
result is the interest for 1 day.

Express the multiplication of this quotient by 18,
which result is the interest for 18 days.
By cancellation, the result is $1.44.

36. Find interest of $300 for 20 days at 8%.
37. Find interest of $450 for 19 days at 10%.
38. Find interest of $1200 for 16 days at 7%.
39. Find interest of $1500 for 25 days at 9%.

40. Find interest of $840 for 7 months 21 days at 6%.

SOLUTION.-Consider the 21 days as .7 of a month.
Proceed as in example 28.

7.7
$32.34

41. Find interest of $660 for 3 mos. 18 days at 6%.
42. Find interest of $340 for 5 mos. 24 days at 8%.
43. Find interest of $800 for 9 mos. 15 days at 4%.
44. Find interest of $140 for 7 mos. 12 days at 5%.
45. Find interest of $600 for 11 mos. 21 days at 7%.
46. Find interest of $500 for 6 mos. 27 days at 10%.
47. Find interest of $600 for 5 yrs. 3 mos. 11 days,
at 5%.

PROCESS.
12 $600.

30 .05
101

3 25.25

$8.413

SOLUTION.-Interest on $600 for 5 yrs.=$600×
.05X5=$150. 3 mos+11 days=101 days. Find
interest for 101 days by cancellation, as in example
35, $8.41%.

$150+$8.413=$158.41.

Find interest of

48. $960 for 2 yrs. 8 mos. 7 days, at 10%.
49. $1440 for 3 yrs. 5 mos. 15 days, at 9%.
50. $60 for 2 yrs. 3 mos. 20 days, at 7%.
SUGGESTION. 71%-15%.

51. $1200 for 4 yrs. 6 mos. 5 days, at 44%.
52. $195 for 8 yrs. 1 mo. 3 days, at 64%.
53. $180.75 for 1 yr. 2 mos. 10 days, at 6%.
54. $47.60 for 2 yrs. 3 mos. 18 days, at 7%.

55. Find the amount of $325.50, for 4 yrs. 6 mos. 15
days, at 6%.

56. Find the amount of $480.90 for 3 yrs. 9 mos. 10
days, at 8%.

57. I bought a lot for $800, and after 2 yrs. 6 mos. I sold
it for $1200. What was the gain, if money was worth 10% ?

58. What amount of money will pay a note of $500,
due in 3 yrs. 6 mos. 20 days, at 10%?

59. I loaned Mr. Jones $800, which he returned in 8
mos. 10 days, with 8% interest. What did he pay me?

60. What is the annual income from an investment of
$10000, which pays 84%?

REVIEW QUESTIONS.

Define interest. Define principal. Define rate of interest. Define
amount. What part of the principal is the interest for one year?

MISCELLANEOUS EXERCISES IN PERCENTAGE.

A. Find commission, or premium, or gain or loss, on
numbers in first column, at 1%, 1%, 1%, 3%, 14%, 22%, 61%, 81%.
B. Find interest on each of the following principals for
the time indicated, at 4%, 4%, 5%, 6%, 7%, 71%, 8%, 9%, 10%.

10.- -$324.125 2y. 5m. 6d.
11.-$862.17 2y. 9m. 17d.
12.-$920.09 1y. 10m. 3d.
13.-$382.11 3y. 6m. 19d.
14.-$809.05 2y. 7m. 21d.

21.-$324.20 4y.
22. -$ 80.50
23.-$192.60
24.-$455.24 2y. Om. 17d.
25.-$128.125 1y. 3m. 22d.
26.-$840.75 3y. 5m. 13d.
27.-$224.375 2y. 9m. 21d.
28.-$800.00 7y. 7m. 7d.
29.-$925.06 10y. 6m.

15.-$395.60 1y. 10m. 12d. | 30.-$708.20 2y. 8m. 24d.

C. Find numbers of which the numbers below are 1%,

11%, 2%, 21%, 21%, 3%, 4%, 5%, 121%, 163%.

D. Find what rate per cent each of the following num-
bers is of the succeeding number.