a. How much water is used in 2 hr. ?

b. If the motor runs two hours every week, what is the annual cost of the water used, at 14¢ per 100 cu. ft.?

c. How many gallons of water are used?

d. If all the water used for this purpose during a year were collected in a tank 12 ft. by 13 ft., how deep would the water be?

COMPUTATION IN HUNDREDTHS

252. Decimals in hundredths are used very generally in business calculations. The merchant calculates his gain or loss as a certain number of hundredths of the cost of the goods. Banks compute interest in hundredths. Agents who sell goods sometimes figure their earnings as a certain number of hundredths of the selling price of the goods. The relations of numbers are expressed generally in hundredths.

Problems involving computation in hundredths usually present one of the two questions of relation between product and factors, namely:

a. Two factors given, to find the product, or,

b. The product and one factor given, to find the other factor; e.g.:

1. A merchant bought pears at $1.60 a bushel and sold them so as to gain .25 of the cost. How much did he gain on one bushel?

Statement of Relation: .25 of $1.60 = gain on one bushel. Here 1.60 and .25 are factors, and the product is to be found. How shall we find it?

2. .40 of the pupils in a school are boys. If there are 600 boys, how many pupils are there in the school?

Statement of Relation: .40 of product and .40 one of its factors.

— pupils = 600 pupils. Here 600 is a How may the other factor be found?

3. A man's salary is $1500. He saves $250. How many hundredths of his salary does he save?

Statement of Relation: of $1500 = $250. Here 250 is a product and 1500 one of its factors. How may the other be found?

In each of the following examples, give the statement of relation and find the answer :

1. A farm worth $4500 rents for .05 of its value. For how much does the farm rent?

2. .90 of the pupils in a class were promoted. If 36 pupils were promoted, how many were there in the class?

3. It cost $24 to decorate a room. The labor cost $18. How many hundredths of the entire expense were for labor?

4. A farmer's crop of apples amounted to 960 bushels, of which 864 bushels were fit for market. How many hundredths of the crop were fit for market?

5. A speculator sold some property for $78,000, and invested .33 of the money in grain and $39,000 in real estate. He put the remainder in the bank.

a. How much did he invest in grain?

b. How many hundredths of his money did he invest in real estate?

c. How many hundredths of his money were left?

6. How many dollars' worth of goods must an agent sell to earn $513.40, if he receives .17 of the value of all the goods which he sells?

7. How many hundredths of $142.60 is $7.13?

8. 24 quarts are how many hundredths of six bushels?

9. A grocer bought 8 bushels of potatoes at 75 cents a bushel and sold them for $7.80. He gained how many hundredths of the cost?

10. Three clerks received wages as follows: A, $15 a week; B, $10 a week and .02 of the amount of his sales; C, .05 of the amount of his sales. What was each clerk's yearly income, if the sales of each amounted to $400 per week?

11. .85 of a certain number is 595. What is .14 of the number?

12. A boy paid .24 of his money for books, .07 of his money for stationery, and .22 of his money for a football. If he then had $3.76 left, how much had he at first?

13. Mr. Markell bought a house for $4200 and sold it for $4830. How many hundredths of the cost did he gain?

14. By selling his automobile for $1860, Dr. Smith received .66% of its cost. What did it cost?

15. The list price of suits for a baseball team was $4.75 apiece. The dealer sold 11 suits for .80 of the list price. How much did he receive for them?

NOTE.

The price at which goods are marked in the price list is called the list price.

16. By selling goods at a reduction of .15 of the list price, a. What part of the list price is received?

b. What is the list price of goods that are sold for $155.55? c. What reduction is made on goods that are sold for $170 ?

17. A contractor makes concrete by mixing 5 barrels of cement, 10 barrels of sand, and 25 barrels of crushed stone. How many hundredths of the mixture is: a. cement? b. sand? c. crushed stone?

PERCENTAGE

254. Per cent means hundredths.

Seven per cent of $100 means .07 of $100, or $7.

Ten per cent of 300 pounds means .10 of 300 lb., or 30 lb. Twenty-five per cent of 24 hours means .25 of 24 hours, or 6

hours.

Thirty-three and one third per cent of 276 means .333 of 276,

or 92.

The sign % indicates per cent; e.g.

255. Oral

19% of 200.19 of 200, or 38.

9% of $80.09 of $80, or $7.20.

% means of 1%, or .001.

% means of 1%, or .00%.

Read each of the following expressions, using the word hundredths instead of the sign %, and find its value:

256. The number of hundredths indicated as per cent is called the rate per cent; the number of which a certain number of hundredths are indicated by the rate is called the base; the product of the base and rate is called the percentage; the sum of the base and percentage is called the amount; the difference between the base and percentage is called the difference; e.g.

25% of $300 is $75. 25% is the rate; $300 is the base; $75 is the percentage; $375 is the amount; $225 is the difference.

257. The relations of product and factors usually determine the method to be employed in solving problems in percentage; e.g.

1. A man bought some land for $4500, and sold it so as to gain 12% of the cost. How much did he gain?

Statement of Relation: 12% of $4500 = gain

.12 of $4500 = ?

.12 and $4500 are factors, and the product is to be found. How may we find it?