124 PROBLEMS-TIME-CARDS Plan the solution and make the computation: 1. If 8 hours of labor are understood to constitute a day's work and a workman receives $1.50 a day on this basis, how much does he receive for 36 hours' work? he receive per hour? For 3 hours' work? How much does NOTE. Fractional parts of a cent should be omitted from the results. 2. On the basis of Exercise 1, how many dollars does a man earn in a week who works 8 hours on Monday, 6 hours on Tuesday, 8 hours on Wednesday, 7 hours on Thursday, 9 hours on Friday, and 4 hours on Saturday? 3. The following table shows the number of hours worked by A, B, C, D in one week at a factory; also their wages per day on the basis of an 8-hour day: On the basis of an 8-hour day, how many days did each man work during the week? 4. What is the average number of hours per day for each man in Exercise 3? 5. What is the average wage according to Exercise 4 for the 6 days? 6. What are the total wages of each for the week? 7. What is the total pay-roll for the four men? 8. How many hours did C's week lack of being six 8-hour days? 9. A man earned $840 a year and spent $780; what part of his earnings did he spend? What is the ratio of his expenditures to his income? PROBLEMS-USEFULNESS OF BIRDS 125 The following table shows the number of birds and the number of insects destroyed by them in a period of 5 days: 1. According to the above table, what was the average number of insects destroyed by the black-billed cuckoos? By the yellow-billed cuckoos? Give the results to the nearest whole number. 2. Find the total number of birds and the total number of insects. What was the average number of insects destroyed per bird? 3. What part of the whole number of insects eaten were caterpillars? 4. If 5 days are taken as the time in which these insects were eaten, what is the average number destroyed per day? 5. A Swanson hawk destroys on the average 100 grasshoppers per day; how many grasshoppers do 300 of these birds destroy in a month of 30 days? 6. Taking the average weight of each insect as 15.4 grains, what is the weight of the insects destroyed in a month? (7,000 grains = 1 lb.) 7. It is estimated that a grasshopper devours daily a quantity of food equal to his own weight; if the grasshoppers had not been killed, how many tons of produce would the farmer have lost in one month? 126 PROBLEMS-USEFULNESS OF BIRDS 1. In 1895 Pennsylvania provided a bounty of 50¢ each on hawks, owls, and certain other birds and animals. In 1 year $60,000 were paid in bounties. How many of the animals were destroyed? 2. Most of the animals destroyed were hawks and owls. Granted that 5,000 chickens are killed annually in Pennsylvania by hawks and owls, and that they are worth 25¢ each, what is the annual loss from the chickens killed? 3. An owl or hawk is supposed to destroy on an average 1,000 mice annually. Granted that mice destroy on an average at least 24 worth of produce annually, how much does one owl or hawk save the farmers annually by destroying mice? 4. According to Exercises 1 and 3, taking all the animals as hawks and owls, how much would the birds, if allowed to live, have saved the farmers of Pennsylvania? 5. According to Exercises 3 and 4, how many dollars would the birds have saved the farmers in excess of what they destroyed in poultry? 6. How many dollars did the State throw away in bounties and in the loss of agricultural products in one year? 7. How many dollars did the State spend for every dollar saved under the Act of 1885? 8. Many birds eat seeds, which, if not destroyed, grow into weeds. Suppose that in your State (for area in square miles, see p. 120) there are 25 seed-eating birds per square mile and that each bird eats oz. of seed per day, how many pounds are destroyed per day? How many tons? At this rate how many tons are destroyed from June 1st to Oct. 31st, inclusive? 9. According to the last questions of Exercise 8, how many car-loads of 60,000 lb. of these seeds are destroyed in your State in a season? Oral. REVIEW AND SUMMARY 127 1. What are the names of the first four places in a whole number? 2. What is the name of the fifth place? The sixth? 3. How many periods are there in a number of 6 places? 4. What is the name of the seventh place in a whole number? What is the name of the third period? Write: 5. Three million, two hundred seventy thousand, sixtyfive. 6. Twenty-five million, ninety thousand, one hundred twenty. 7. Eighty-seven million, eighty-seven thousand, fortynine. 8. Twenty million, forty thousand, one hundred forty. 9. What is a ratio? Give several examples. 10. What other questions mean the same as: the ratio of 9 to 27?" "What is II. A man invested $500 and received an income of $25. What is the ratio of the income to the investment? 12. Illustrate what is meant by average. Name two kinds of problems in which it has been used. 13. Four cars together carry 240,676 lb. of granite; what is the average number of pounds which one car carries? 14. In 1884 the export from the United States of iron and steel and articles manufactured from them amounted to $21,900,000; in 1900 the value of the same exports was $121,900,000. What was the difference between the values. of the exports for the two years given? 15. The price of wheat was: Monday, $.671; Tuesday, $.68; Wednesday, $.661; Thursday, $.675; Friday, $.67%; Saturday, $.667. Find the average price for the week. PERCENTAGE Rate Per Hundred 1. Find the cost of 600 coats at $492 per hundred. $492 6 2. Find the cost of 350 chairs at $112 per hun- $112 dred. 31 3. A boy is permitted to fish in a pond on condition that he gives the owner 30 per hundred of the fish caught. He caught 120 fish. How many did he give the owner? SUGGESTION: 30 of the hundred equal parts of the fish caught =% of 120 = ? 4. Fractions with the denominator 100 are extensively used in practical and business arithmetic. 5. 1 = τόσο Express as hundredths: = 32. Write as an ordinary fraction 5 hundredths. Reduce it to its lowest terms. 33. Write as an ordinary fraction 12 hundredths. Then cancel 12 from both terms. |