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13. If a piece of property is bought for $ 6000 and the taxes and insurance on it are $ 96 annually, what must the monthly rental be in order that the return may be 12% of the investment?
14. Find the corresponding selling prices if goods are marked as follows:
163 % off on goods marked $ 2.50
15. Which is the greater : 42 % of 51 or 51 % of 42? The difference is how many per cent less than 42 ? The difference is how many per cent less than 51 ?
16. In a school whose enrollment is 525, 18 pupils were ab sent on Monday, 17 on Tuesday, 14 on Wednesday, 19 on Thursday, and 22 on Friday. What was the percentage of attendance for each day? What was the average percentage of attendance for the week ?
17. In room A are 33 pupils, 31 of whom have been present every day ; in room B are 42 pupils, 39 of whom have been present every day; in room C are 26 pupils, 24 of whom have been present every day. What room has the highest percentage of attendance ?
18. An orchardist planted 120 trees of which 14 died; he planted 70 raspberry bushes and lost none; he planted 1000 grapevines and lost 35. What per cent of each kind planted survived ? What per cent of the entire number of trees and plants set out lived?
19. A nurseryman bought 1000 avocado seeds at ten cents apiece. He figured that 10 % of them would not germinate and that frost would kill 15 % of the young trees. For how much should he sell each tree to clear $ 1000 ?
20. If 58 members of a class are boys and 67 are girls, what is the percentage of each ?
21. If 217 words out of 250 are spelled correctly, what is the percentage of correctly spelled words?
22. If iron ore yields 62 % of pure metal to the ton, how much iron can be obtained from 40 tons of ore ?
23. Two men form a partnership. One agrees to furnish 40% of the capital and the other 60 %. If the first furnishes $ 2500, what does the other furnish ?
24. A farmer received 40 % of a crop as rent for his land. If his share of the crop amounted to 4000 bushels, what was the amount of the entire crop ?
25. A man owning a f interest in a mine sold į of his interest. What per cent of the mine did he still own?
26. If wages are increased 15 %, what is the wage of a man who has been getting $ 62 a week ?
27. What is the percentage of error in taking one yard equal to 35 inches ?
28. In a solder made up of 5 parts zinc, 2 parts tin, and 1 part lead, what is the percentage of each constituent ?
29. The following amounts of metal are melted together to form a soldering alloy : 18 pounds of tin, 37} pounds of lead, 75 pounds of bismuth, and 194 pounds of cadmium. What is the percentage of each ingredient ?
30. A 100-gallon mixture of alcohol and water is 70 % alcohol. How much alcohol must be added that the percentage of alcohol be increased to 80 % ?
Discount Commercial discount is a reduction from the list price of an article or from the amount of a bill of goods.
The net price is the amount of the bill after the discount has been made.
EXAMPLE What is the net amount of a bill of $ 325 after a discount of 20 % has been deducted ? Amount of bill
$ 325 Less 20 % or of $325
65 Net amount
Exercise Find the net prices of goods billed as follows, with discounts as stated : 1. $ 25 .
10% off 6. $ 62.50 . 20% off 2. $14. 20% off 7. $ 49.
5% off 3. $ 62 15% off 8. $ 55.50
2% off 4 $ 70 . 10% off 9. $ 150
8% off 5. $ 48 15 % off 10. $ 206
Interest is money paid for the use of money.
The rate is the number of hundredths of the principal paid for its use for one year.
Simple Interest Interest is ordinarily computed on the basis of 12 months of 30 days each, or 360 days. It is then called simple interest or common interest.
Rule. - To find the interest multiply together the principal, the rate, and the time expressed in years. EXAMPLE 1. Find the interest on $575 for 3 years at 4%.
$ 575 Principal
3 Time (in years)
EXAMPLE 2. Find the interest on $ 288 for 2 yr. 7 mo. at 5 %.
$ 288 Principal
2 Time (in years)
7.20 Interest for 6 mo.
1.20 Interest for 1 mo.
$ 37.20 Interest for 2 yr. EXAMPLE 3. Find the amount if $ 475 is at interest for 4 yr. at 6 %
$ 475 Principal
4 Time (in years)
Find the interest and amount in each of the following: