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21. A man saved $750 more this year than last year. Last year he saved $2000. What is the per cent of increase?

22. A man weighed 160 lb. in September and 10 lb. more the next April. What per cent had he gained on his weight in September?

23. A farm of 300 acres has 48 acres of woodland. What per cent of the farm is woodland?

24. In a certain school 22 of the pupils are in the sixth grade. There are 275 pupils in the school. What per cent are in the sixth grade?

25. A contractor has agreed to erect a building for $48,000. He has been paid $18,000 on account. What per cent of the contract price has he been paid?

26. In an arithmetic class it is planned to solve 550 problems in a certain number of days. All but 44 have been solved. What per cent of the problems remain to be solved? What per cent of them have been solved?

27. A baseball team has won 32 games and lost 28 games. What per cent of the total number of games has it won? What per cent has it lost?

28. A cubic foot of ice weighs 57 lb. A block of ice containing 4 cu. ft. loses 284 lb. by melting. What per cent does it lose?

29. A cubic foot of water weighs 62 lb. From a tank containing 16 cu. ft. there is drawn off an amount of water that would weigh 125 lb. What per cent of the water is drawn off?

30. To a class of 32 pupils 8 more are admitted. What per cent of the original number are admitted? What per cent of the present number are admitted? If 10 pupils are now taken out, what per cent are taken out?

228. One Number is a Given Per Cent of what Number? Because the percentage is the product of the base and the rate (§ 225), therefore

The base equals the percentage divided by the rate.

For example, if 15% of a number is 390, what is the number?

390 15% 39,000 ÷ 15 = 2600. Ans.

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The simple equation may be used in cases of this kind, it being explained that 2 x means 2 times some number that is to be found.

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Of what numbers are the following the given per cents?

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10. What is the number of which $75 is 125%? That

is, what number increased by 25% equals $75?

11. What number increased by 331% equals $480 ?

12. What number increased by 50% equals $600 ?

13. $260 is 4% more than (or 104% of) what number? 14. $420 is 5% more than what number?

15. $375 is 75% of what number? That is, what number decreased by 25% equals $375 ?

16. What number decreased by 25% equals $900 ?

17. $435 is 6% of what sum of money?

18. What number increased by 331% equals $500?

19. A city increased 14% in population in ten years. The increase was 3332. What was the population before this increase?

20. A city increased 16% in population in ten years. The increase was 5200. What was the population both before and after this increase?

21. The weekly pay roll in a certain shop was increased 8%. The increase amounted to $192. What was the pay roll before the increase?

22. The attendance at a certain school has increased 14, which is 5% of the attendance last year. What was the attendance last year?

23. A lady paid 95 less for groceries this week than last week. This was a decrease of 10%. How much did she pay last week? this week?

24. A man purchased this year 24 tons of coal less than he did last year, a reduction of 121%. How many tons did he purchase last year? this year?

25. In a certain month there were seven stormy days, or 25% of the total number of days. What month was it?

26. A man sold a farm at a profit of 16% on the cost, thereby making $540. What did the farm cost him?

27. A man has a meadow to mow. After he has mowed 24 acres, 37% of the work is done. How many acres has he then to mow?

28. A man buying a farm is told that if he will pay cash he can get it for 61% less, and can thereby save $500. What would the farm then cost him?

29. A state is building a certain number of miles of road this year. It has already finished 33% of it, or 280 miles. How many miles is it to build this year?

228. One Number is a Given Per Cent of what Number? Because the percentage is the product of the base and the rate (§ 225), therefore

The base equals the percentage divided by the rate.

For example, if 15% of a number is 390, what is th number?

390 15% = 39,000 ÷ 15 = 2600. Ans.

The simple equation may be used in cases of this kind, it beir explained that 2x means 2 times some number that is to be found.

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