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The yearly interest of a sum at 6 per cent. is equal to part of the principal added to 250 dollars; what is the principal?

Suppose the principal to be
Rate per. cent.

Interest for 1 year,

of 500 =

Excess only,

Ans. $25000. 500 dollars.

6

30100

25

5 dollars.

Here the excess over is only five dollars interest instead of 250.

Now say, if 5 excess of interest, arises from 500 principal; what did 250 excess arise from?

5 500 250 to a fourth number.

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Of a certain sum lent, I received one fourth, one fifth, and one sixth, which amounted to 185 dollars; what was the Answer, 300 dollars.

sum lent?

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.

A and B have a salary each alike for 3 years; A saves of his wages, but B spends the whole of his and one third more, falls in debt fifty dollars yearly, and at the end of 3 years, after settling his accounts, has only 20 dollars left of a present given by his uncle at the commencement of business; what was the salary? And how much the present? Answer, the salary was 150 dols. each.

The present was 170 dollars to B.

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On the 25th day of October 1815, while penning this lesson, I find that one fifth of the years I have lived, multiplied by 6, and the fourth of my years added to that product, make 87; what is my age? Answer, 60 years.

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LESSON 6.

Says George to Harry, I have a sum of money to buy books; the and a of which will make 4 dollars and

183

50 cents; if you will tell me how much I have, 2 dollars Answer, 9 dollars.

shall be yours.

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Is when we use two suppositions: and if we miss in both, observe the nature of the errors and work accordingly. When the errors are both less, or both greater than the given number, they are alike; but if one be greater and the other less than the given number, they are unlike.

RULES.

1. When the errors are alike, take their difference for a divisor, and the difference of their products for a dividend. 2. When the errors are unlike, take their sum for a divisor and the sum of their products for a dividend.

LESSON 7.

AB and C would divide 250 dollars between them in such manner that B may have 7 dols. 50 cents more than A, and C 10 dols. more than B; how much must each man have? Answer, A must have 75 dols. B, 82.50 and C, 92.50. OPERATION.

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Having proceeded according to the proportions mentioned in the question, and placed the suppositions and errors as here represented, multiply them crosswise, that is, multiply the first error by the last supposition, and the last error by the first supposition.

Supposi.

Error.

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Proof, 250.00

LESSON 8.

"A saddle is worth 50 dollars: two horses are of different value: when the saddle is on the first horse it raises his value to double the second; but when it is on the second horse, his value is triple the first: What is the value of each horse?

Ans. The price of the first horse is 30 dollars, and the second 40."

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The price of the second horse of 88
The saddle,

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Their combined value,

94

Three times the value of the first horse 38x3=114

The difference between 114 and 94 is the

first error,

20

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Their combined value,

The price of the second horse of 92
The saddle,

Their combined value,

Three times the value of the first 42*3=

The difference between 126 and 96 is the

second error,

Supposi. Error.

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30

1st. 38 20

2nd. 42

X3

30

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"A boy stealing apples being taken by mad Tom, gave over half he had stolen, and Tom gave him back 10; in his return home, he was met by raving Ned, who took from him one half of what he had left, and returned him back 4; after that, unluckily, positive Jack meets him, and takes away one half the remainder, giving back 1; at last many getting safe away, he finds he has 18 left: How had the boy at first? Answer, 100,"

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