Εικόνες σελίδας
PDF
Ηλεκτρ. έκδοση

Estimating Results

You have already learned several methods for checking results. Another method, which quickly detects absurd answers, is first to estimate the result. After some practice you will acquire much skill in determining beforehand about what the answer will be.

Many times an estimate is all that is desired. Often a person wishes to know only "about how much " something will cost, or "about how many square feet" there are in a piece of land.

[blocks in formation]

Make a chart like this and fill in the last two columns.

[blocks in formation]

The Solution of Problems

These five suggestions will prove helpful in solving problems.

1. Read the problem carefully until you understand what it says and what is asked for.

2. See how what is stated in the problem is connected with what is asked for and decide what process you are to use. 3. Estimate the result when possible.

4. Then, and not until then, use your pencil and do your work accurately.

5. Check the result.

PROBLEMS

1. The daily sales at a grocery store for one week were as follows: $175.50, $214.75, $208.34, $235.18, $194.26, $275.89. How much were the total sales for the week?

2. How much was the average daily sale that week? 3. An automobile bought for $2,000 was sold for $1,275. How much was the loss in price?

4. A train ran 522 miles in 12 hours. How many miles an hour did it average?

5. A woman gave a clerk a ten-dollar bill in payment for 8 yards of cloth at 69¢ a yard. How much change did she receive?

6. Oranges bought at 35¢ a dozen were sold at 5¢ each. How much did the fruit dealer make on 7 dozen of these oranges?

7. What is the value of a carload of 850 bushels of wheat at $1.25 a bushel?

8. A 38-acre farm sold for $6,650. What was the average price per acre?

9. Knives are selling at the rate of $3.60 per dozen. At what rate is this per hundred?

How much

10. A woman bought a washing machine by paying $10.00 down and then $5 a month for 17 months. would she have saved by paying $80 cash?

11. A woman rented a house for $35 a month and then rented one of the rooms for $4 a week.

year's rent did she have to pay herself?

How much of the

12. A merchant bought silk at $1.25 a yard and sold it at $1.70 a yard. How many yards did he sell to make $27?

13. One plot of 30 acres of land was sold for $1,860, and another plot of 50 acres was sold for $2,600. First estimate the price of each plot per acre, then find the actual cost and see how nearly right your estimates were.

14. A boy bought a second-hand bicycle for $15.00. He used it all summer, paying $2.50 for a new tire and $1.25 for repairs. He sold the bicycle then for $16.00. How much did his riding cost him for the summer?

15. A gasoline pump delivered 23 five-gallon orders, 16 three-gallon orders, 14 two-gallon orders, and 10 single gallons. How much was this gasoline worth at 24¢ a gallon? 16. Soup can be bought for 12¢ a can or for $1.25 a dozen How much will be saved on 15 dozen cans by buying them by the dozen?

cans.

17. A fruit dealer bought 75 baskets of blueberries at 18¢. He sold 50 baskets at 25¢ each and 25 baskets at 20¢. How much did he make on the blueberries?

18. A man earns $2,000 a year and his expenses average $1,625 a year. At this rate how long will it take him to save $1,500?

[graphic][merged small]

1. The Grove Hill Radio Club has a membership of 30 boys. Each boy pays dues of 25¢ a month. To how much does this amount in a year?

2. Their chief expenses are $5 a month for rent, $1 a month for light, and $4 a year for magazines. To how much does this amount in a year?

3. By how much do their receipts exceed their expenses each year?

4. To raise money with which to purchase a one-bulb set, the Radio Club gave an entertainment, selling 350 tickets at 25¢ each. The expenses were: hall, $15; film, $25; printing, $4.50. How much did the boys make? 5. Here is a list of 1 variable condenser 1 vario coupler

1 rheostat .

1 lightning protector

1 double head-set

the material they bought for the set.

$3.50 1 bulb

$5.00

5.00

1 socket

. .75

1.00

1 switch arm

[ocr errors]

. .60

[merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small]

100 ft. 7-strand aërial wire at 1¢ a ft. .

50 ft. #14 ground wire at 2¢ a ft.
6" x 14" bakelite at 2¢ a sq. in.

Find the cost of the one-bulb set.

[ocr errors]
[ocr errors]

6. After paying for this set, how much was left from the proceeds of the entertainment?

DIVISIBILITY

These tests for divisibility will prove useful in reducing fractions, in cancellation, and elsewhere in arithmetic.

1. All even numbers are divisible by 2.

2. If the sum of the figures of a number is divisible by 3, the number is divisible by 3.

258 is divisible by 3, because the sum of 2 and 5 and 8- that is, 15-is divisible by 3.

3. If the last two figures of a number are zeros, or if they form a number which is divisible by 4, the given number is divisible by 4.

136 is divisible by 4, because 36 is divisible by 4. 4. Any number ending in 0 or 5 is divisible by 5. 5. Any number ending in 0 is divisible by 10.

ORAL EXERCISES

Tell whether these numbers are divisible by 2, 3, 4, 5, 10.

[blocks in formation]

What does the denominator of a common fraction show?

What does the numerator show?

What is a proper fraction? an improper fraction? a mixed number? Give examples of each.

How is a fraction affected if the numerator is multiplied by a given number? if the numerator is divided by a given number? if the denominator is multiplied by a given number? if it is divided by a given number?

« ΠροηγούμενηΣυνέχεια »