19. $450 for 19 mo. (18 mo. +1 mo.).

Find the interest at 6% on :

40. Find the interest on $562.50 for 1 yr. 10 mo. 15 da.

57. $5175 for 4 yr. 10 mo. (60 mo.

-2 mo.).

58. $640 for 3 yr. 2 mo. (40 mo. -2 mo.).

59. $1240.60 for 2 yr. 9 mo. 15 da.

.

From the interest on any principal at 6 %, the interest at other rates may be found by adding or subtracting aliquot

61. $216 from July 25, 1891 to Sept. 10, 1893, at 6 %. 62. $348 from Jan. 16, 1893 to Feb. 4, 1896, at 7 %. 63. $650.40 from April 19, 1903 to March 4, 1906, at 4 %. 64. $1200 from Nov. 2, 1900 to Oct. 19, 1903, at 41 %. 65. $1800 from Aug. 25, 1902 to June 1, 1906, at 41 %. 66. $476.25 from Aug. 19, 1902 to June 1, 1906, at 8%. 67. $1600 from Sept. 25, 1902 to May 18, 1906, at 41 %. 68. $164.88 from July 3, 1903 to Dec. 31, 1905, at 5 %.

The One Dollar Six Per Cent Method

The interest on $1 for 30 da. (1 mo.) = $.005.

The interest on $1 for 1 da. (3 of $.005) = $.0001.

Change the time to months and days. Since the interest on $1 for 1 mo. is of a cent and for 1 da. of a mill, the interest on one dollar will be as many cents as there are months and as many mills as there are days. Multiply the result by a number equal to the number of dollars in the principal.

Written Work

1. What is the interest on $240.60 for 2 yr. 3 mo. 13 da. at 6%?

$.1371

Interest on $1 at 6% for 2 yr. 3 mo. 13 da. =

Interest on $240.60 240.60 × $.137%, or $33.00

=

Find the interest:

26. At 5% on $237.50 from Jan. 3, 1906 to Sept. 11, 1908. 27. At 7% on $ 309.75 from May 5, 1905 to Jan. 12, 1907. 28. At 71% on $7500 from June 12, 1907 to Nov. 1, 1909. 29. At 61% on $ 6225 from Oct. 11, 1907 to Mch. 1, 1910. 30. At 41% on $750 from Feb. 12, 1907 to Aug. 9, 1911. 31. At 8% on $ 2900 from July 1, 1906 to May 10, 1910. 32. At 4% on $3675 from June 4, 1907 to Apr. 1, 1910. 33. At 3% on $ 290.80 from Nov. 12, 1907 to Apr. 10, 1912. 34. At 5% on $875 from June 11, 1907 to Mch. 11, 1912. 35. At 51% on $8000 from Apr. 1, 1907 to May 9, 1912. Solve the following problems by both the six per cent methods and compare results as to time and accuracy.

Find the interest from the following conditions:

42. Find the amount of $1275.80 for 1 yr. 7 mo. 24 da. at 7%.

43. Find the interest of $4780 from April 1, 1907 to Sept. 18, 1909, at 61%.

44. On the 16th of September, 1907, I borrowed $3600 at 8%. How much will settle the loan April 1, 1909?

45. July 28, 1907, a broker borrows $3200 at 5% interest and on the same day loans it at 71% interest. If full settlement is made April 1, 1909, how much will the broker make by reloaning the money?

PROBLEMS IN SIMPLE INTEREST

Finding the principal.

Written Work

1. What principal invested at 4% per annum will yield an annual income of $200 ?

Since the interest on $1 for 1 year at 4% is $.04, as many dollars must be invested to yield $200 per year as $.04 is contained times in $200. $200 $.04 5000. Hence, $5000 must be invested.

=

The principal equals the given interest divided by the interest on $1 for the given time at the given rate.

2. What principal at 41% will gain $213.75 interest in 4 yr. 9 mo.?

3. What principal at 5% will gain $120.70 interest in 3 yr. 6 mo. 18 da.?

4. What principal at 8% will gain an interest of $163.20 from Sept. 30, 1903 to June 12, 1905?

5. A man gave his note April 1, 1901, at 6%. When he settled the note Aug. 13, 1903, he paid $195.25 interest. What was the principal, or face of the note?

Finding the rate.

Written Work

1. At what rate must $500 be invested to yield $75 interest in 2 yr. 6 mo. ?

Since the interest on $500 for 21 yr. at 1% is $12.50, it will require a rate of as many per cent to yield $75, as $12.50 is contained times in $75, or 6%.

The rate equals the given interest divided by the interest for the given time at 1%.

2. The interest on $1125 for 3 yr. 4 mo. 24 da. is $229.50. What is the rate per cent?