If the rate had been 7 %, of the above would have been added to it. How much would have been added if the rate had been 8%? What would this interest have been? If the rate had been 5%, of the above would have been subtracted from it. How much would have been subtracted if the rate had been 4 %? What would the interest have been at 4 %?

EXERCISES

Find the interests for the following by the bankers' method given in Art. 259:

1. $4000 at 6% for 2 yr. 2 mo. 10 da.

2.

3.

$ 460 at 6% for 3 yr. 4 mo. 10 da.

$2400 at 6% for 1 yr. 3 mo. 10 da. 4. $820 at 6 % for 1 yr. 5 mo. 20 da. $3200 at 7% for 1 yr. 4 mo. 20 da. $ 1650 at 5% for 2 yr. 3 mo. 5 da.

5.

6.

11.

One of Mr. McClure's customers paid a debt of $ 86, 3 yr. 7 mo. after the debt was due. If Mr. McClure could have loaned this money at 6%, what should the customer have paid him in addition to the original bill of $86?

12. If $ 350 is borrowed to-day at 7 % for 60 da., when will it be due and what will be the interest?

260. Interest Tables.-Most men who compute interest a great deal, as loan agents and bankers, use interest tables such as the one given on page 231. These tables are often larger so as to give the interest for any day from 1 up to 30 and for several years. They also give the interests for various rates, as 2%, 2%, 3%, 3%, etc., up through 10% or 12 %.

In using the table, place a small card or a straight piece of paper under the line containing the number wanted. Do not rely upon tracing it out with a pencil or the finger. Most errors in the use of tables are due to such tracings with a finger or a pencil.

Find the interest on $ 2350 at 6 % for 1 yr. 3 mo. 25 da.

Interest $2000...... 1 yr. (10 X int. $200).

=

Interest

300.....

1 yr.

$120.00 18.00

From the table on the opposite page find the interests at 6% on the following loans:

DA. $ 100

1234567

9

10

11

12

$200

6% INTEREST TABLE

$300 $400 $ 500 $ 600 $700 $800 $900 DA.

12345678

0.017 0.033 0.050 0.067 0.083 0.100 0.117 0.133 0.150 0.033 0.067 0.100 0.133 0.167 0.200 0.233 0.267 0.300 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450 0.067 0.133 0.200 0.267 0.333 0.400 0.467 0.533 0.600 0.083 0.167 0.250 0.333 0.417 0.500 0.583 0.667 0.750 0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800 0.900 0.117 0.233 0.350 0.467 0.583 0.700 0.817 0.933 1.050 8 0.133 0.267 0.400 0.533 0.667 0.800 0.933 1.067 1.200 0.150 0.300 0.450 0.600 0.750 0.900 1.050 1.200 1.350 0.167 0.333 0.500 0.667 0.833 1.000 1.167 1.333 1.500 10 0.183 0.367 0.550 0.733 0.917 1.100 1.283 1.467 1.650 11 0.200 0.400 0.600 0.800 1.000 1.200 1.400 1.600 1.800 12 13 0.217 0.433 0.650 0.867 1.083 1.300 1.517 1.733 1.950 13 14 0.233 0.467 0.700 0.933 1.167 1.400 1.633 1.867 2.100 14 15 0.250 0.500 0.750 1.000 1.250 1.500 1.750 2.000 2.250 15 0.267 0.533 0.800 1.067 1.333 1.600 1.867 2.133 2.400 16 17 0.283 0.567 0.850 1.133 1.417 1.700 1.983 2.267 2.550 17 18 0.300 0.600 0.900 1.200 1.500 1.800 2.100 2.400 2.700 18 19 0.317 0.633 0.950 1.267 1.583 1.900 2.217 2.533 2.850 19 20 0.333 0.667 1.000 1.333 1.667 2.000 2.333 2.667 3.000 20. 21 0.350 0.700 1.050 1.400 1.750 2.100 2.450 2.800 3.150 21 22 0.367 0.733 1.100 1.467 1.833 2.200 2.567 2.933 3.300 22 23 0.383 0.767 1.150 1.533 1.917 2.300 2.683 3.067 3.450 23 24 0.400 0.800 1.200 1.600 2.000 2.400 2.800 3.200 3.600 24 25 0.417 0.833 1.250 1.667 2.083 2.500 2.917 3.333 3.750 25 26 0.433 0.867 1.300 1.733 2.167 2.600 3.033 3.467 3.900 26 0.450 0.900 1.350 1.800 2.250 2.700 3.150 3.600 4.050 27 28 0.467 0.933 1.400 1.867 2.333 2.800 3.267 3.733 4.200 28 29 0.483 0.967 1.450 1.933 2.417 2.900 3.384 3.867 4.350 29

16

Mo. $100 $ 200

1234567BROE

$300 $400 $500 $600 $700 $ 800 $900 Mo.

1

123456789CE

0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000 4.500 1.000 2.000 3.000 4.000 5.000 6.000 7.000 8.000 9.000 1.500 3.000 4.500 6.000 7.500 9.000 10.500 12.000 13.500 2.000 4.000 6.000 8.000 10.000 12.000 14.000 16.000 18.000 2.500 5.000 7.500 10.000 12.500 15.000 17.500 20.000 22.500 3.000 6.000 9.000 12.000 15.000 18.000 21.000 24.000 27.000 3.500 7.000 10.500 14.000 17.500 21.000 24.500 28.000 31.500 8 4.000 8.000 12.000 16.000 20.000 24.000 28.000 32.000 36.000 9 4.500 9.000 13.500 18.000 22.500 27.000 31.500 36.000 40.500 5.000 10.000 15.000 20.000 25.000 30.000 35.000 40.000 45.000 10 11 5.500 11.000 16.500 22.000 27.500 33.000 38.500 44.000 49.500 11

10

12345

YR. $100 $200 $300 $400 $500 $ 600 $ 700 $800 $900

YR.

6.00 12.00 18.00 24.00 30.00 36.00 42.00 48.00 54.00
12.00 24.00 36.00 48.00 60.00 72.00 84.00 96.00 108.00
18.00 36.00 54.00 72.00 90.00 108.00 126.00 144.00 162.00
24.00 48.00 72.00 96.00 120.00 144.00 168.00 192.00 216.00
30.00 60.00 90.00 120.00 150.00 180.00 210.00 240.00 270.00

12345

261. Compound Interest Table.-Tables are even more useful in finding compound than simple interest. The following table gives the amount of $1 compounded at the rates and for the time stated in years. How can the table be used if the interest is compounded semiannually?

Yr. 2 per cent 3 per cent 3 per cent 4 per cent

5 per cent 6 per cent

12345

1.025000
1.050625

1 030000
1.060900

1.035000 1.040000 1.050000 1.060000 1.071225 1.081600 1.102500 1.123600 1.076891 1.092727 1.108718 1.124864 1.157625 1.191016 1.103813 1.125509 1.147523 1.215506 1.262477 1.131408 1.159274 1.187686

1.169859

1.216653

1.276282 1.338226

16 1.484506 1.604706 1.733986 1.872981 17 1.521618 1.652848 1.794676 1.947901

1.559659 1.702433 1.857489 19 1.598650 1.753506 1.922501 2.106849 20 1.638616 1.806111 1.989789 2.191123 2.653298 3.207136

2.526950

3.025600

2.025817

2.406619

2.854339

EXERCISES

Use the above tables in the following:

1. Find the amount of $1000 compounded annually at 4% for 6 yr.; for 13 yr.; for 17 yr.

2. Find the amount of $400 compounded annually at 3% for 4 yr.; for 7 yr.; for 15 yr.

3. Find the amount of $1000 compounded annually at 3% for 3 yr.; for 8 yr.; for 10 yr.

4. Find the amount of $500 compounded semiannually at 5% for 2 yr.; for 4 yr.; for 5 yr.

262. Interest Graph.-Interests can be approximated quite accurately by the above graph. Use the graph in solving the following exercises.

EXERCISES

1. Find the interest on $900 at 3 %;

at 6%; at 4%. 2. Find the interest on $ 650 at 5%; at 4 %; at 6%. 3. What principal will produce $ 28 per year at 4%? at 5%? at 3 %?

4.

What principal will produce $35 per year at 7 %? at 4%? at 6%?

5. Make an interest graph like the above for the same principals at 2%; at 3%; at 4%.

6. Make up problems like Exs. 1-4 to be solved from your graphs. Verify all your results.