PROBLEMS AND EXERCISES IN DECIMALS 331 1. A man bought a ton of hard coal for $6.35, a ton of soft coal for $4.50, and a load of kindling for $1.50. How much did the coal and kindling cost? 2. James lives .75 mi. north, and Fred, .35 mi. south of the schoolhouse. How far apart do the boys live? 3. Find the cost of 5 barrels of flour at $4.75 a barrel. 4. One street car line has 4.85 miles of track; another 6.55 miles, and a third 7.5 miles. How many miles of track are there? 5. A farm is divided as follows: cornfield, 66.75 acres; oatfield, 42.6 acres; meadow, 24.5 acres; grove, 20.25 acres; vegetable garden, 4.4 acres; building lot, 1.5 acres. How many acres are there in the farm? 6. A bushel of potatoes contains 47.34 lb. water, 10.8 lb. starch, .54 lb. ash, 1.26 lb. proteid, and .06 lb. fat. How much does a bushel of potatoes weigh? 66 Begin on the right and add as with whole numbers. Place the decimal point (.) in the sum just beneath the points in the numbers to be added (addends). 47.34 lb. 10.80 623.21 4561.38 685.329 365.250 1. How much does the water in the 5 foods weigh? The fat? The ash? The proteid? The starch? 2. How much does the oatmeal weigh? The cornmeal? The rye-meal? The rice? The macaroni? 3. What is the weight of all the parts of problem 1? 4. Ten pounds of apples contain 8.46 pounds of water and 10 pounds of bananas contain 7.53 pounds of water. How much more water is there in 10 pounds of apples than in 10 pounds of bananas? First, subtract as with whole numbers. just beneath the points in the minuend MULTIPLICATION OF DECIMALS 333 1. A pound of butter contains 15.6 oz. of fat. How many ounces of fat are there in 3 pounds of butter? 2. In one pound of eggs there are 1.79 oz. of shell. How many ounces of shell are there in 5 pounds of eggs? 3. How many minutes in .05 hour? 4. A lot is 125 feet deep and 12.5 feet wide. What is its area? 5. A square-cornered box is .7 of a foot long, .5 of a foot wide and 3 of a foot deep. What is the area of the top? Of the side? Of the end? Of the entire surface? 7. How may a number be multiplied quickly by 10? 9. In problem 8, how many decimal figures are there in the product of (2)? Of (3)? Of (4)? Of (5)? Of (6)? 10. In problem 8, how many decimal figures are there in both the multiplicand and multiplier of (2)? Of (3)? Of (4)? Of (5)? Of (6)? 11. How may one quickly tell how many decimal places there will be in the product of two decimals? PERCENT EXPRESSED AS FRACTIONS 335 1. What part of a dollar is 1 cent? 9 cents? 31 cents? Another term for hundredths is percent. 1 hundredth of a dollar = 1 percent of a dollar. 9 hundredths of a dollar = 9 percent of a dollar. Instead of the word, percent, the sign, %, is often used. 9 percent of a dollar may be written 9 % of a dollar. 31 percent of a dollar may be written 31 % of a dollar. Hundredths of anything may be expressed in any of the following ways: 100 17 bu., .17 bu., 17 percent of a bu. or 17 % of a bu. 130 lb., .03 lb., 3 percent of a lb. or 3% of a lb. 2. Write first with the percent sign, then as decimals: 3. Write first as common, then as decimal fractions: 4 5 100 4. Write first as hundredths, then with the sign, %: 5. Write first as decimals, then with the sign, %: |