26 May Maths I

MATHS Dr. T.K. Jain. AFTERSCHOOOL M: 9414430763 [email protected] www.afterschool.tk www.afterschoool.tk

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What lease number may be added or substracted in 14,17,34,42 to make them proportional? • Use hit and try. • If we deduct 2 from each of these, they become: 12,15, and 32 , 40, now if we multiply 12 with 40 and 15 with 32, they are equal = 480 – so now it is proportional.

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Price of scooter and moped are in the ratio of 9:5, if scooter costs 6800 more than moped, what is the price of schooter and moped? • The difference is 4. , if four is difference, price of scooter is 9, make an equation with this. • 9/4*6800 = 15300, • Similarly if difference is 4, price of moped is 5, if difference is 6800, price is: • 5/4*6800 = 8500. (their difference is 6800). Ans. (15300-8500 = 6800)

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I get 10% on an item. If I sell it at double the price, what is my profit in percentage? • Assuming, my cost is 100, selling price is 110. Now if I double price, it becomes 220. My profit is 120. My profit is : 120% profit.

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18 workers make 900 units in 10 days. How many workers will be required to complete 660 units of work in 12 days? • Step: - what is being asked – identify that. What is asked is number of workers. Take that first. • 18*660/900*10/12 (remember the law, more the work, more workers will be needed, less the days, more workers will be needed). • 11 Ans.

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10 pipes fill up a tank in 24 minutes. If 2 pipes go out of order, how much time will it take? • First identify what is being asked: it is time. So first put time: • Multiply with no of pipes. – if no. of pipes will reduce, time will go up – so put bigger figure upside. • 24*10/8 = 30 Ans.

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10 pipes fill up a tank in 24 minutes. If 2 more pipes are added, how much time will it take? • First identify what is being asked: it is time. So first put time: • Multiply with no of pipes. – if no. of pipes will increase, time will go down – so put smaller figure upside. • 24*10/12 = 20 Ans.

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With Rs. 1000, I can buy 4 trousers or 8 shirts. How much will I need to buy 3 trousers and 3 shirts? • Price of one trousers is 250, that of one shirt is : 125. • Multiply these by 3 each, and add up, • We get: 750+375 = 1125Ans.

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20 items of A costs 30 items of B, 20 items of B costs 40 items of C, 80 items of C costs 160. What is the cost of 9 items of A in Rs.?

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Cost of C = 2 per item. 20 items of B costs: Rs. 80. 1 item of B costs : 4 20 items of A costs 120, One item of A costs 6. So cost of 9 items of A = Rs. 54 Ans. www.afterschoool.tk

25 men take 25 days of 8 hours each to do a piece of work, how many days of 4 hours each would 15 women take, if it is given that 2 women do as much as 4 men?

• Step 1: what is asked – just write that first. Compare everything with that. Here we have been asked asked to calculate days, so compare hours and no. of persons to days. More hours, means less days. More workers, means less days. • No. of women: 15*4/2 = 30 Men. • Either convert all women to men or convert men to women. • 25*8/4*25/30 = 41.66 so 42 is ans. www.afterschoool.tk

30 children complete onethird of a work in 20 days. How many men should be employed to finish the remaining work in 20 days – if it is given that one men works equal to 2 children?

• Total work: 20*3 = 60 children days. • Remaining days: 40. ; first write downs what is asked (present figure) then compare it with days – less the days – more the children would be required. • 30*40/20 = 60 children should be employed. • That means, 30 men should be employed. Ans. www.afterschoool.tk

1350 liters of milk is consumed by 70 children in 30 days, how much milk will be required for a 28 day camp involving 95 children? • What is being asked: quantity of milk – so write it first. • More the children, more the milk required so 95/70 • Less the days, less will be milk consumption –so – 28/30 • 1350*95/70*28/30 = 1710 Ans. www.afterschoool.tk

15 men take 21 days of 8 hours each to do a work, how many days of 6 hours each would be required by 21 women, if 3 women work as much as 2 men?

• Step 1: identify what is asked: days. • So write the days first: • More the men, less the days - less the hours, more the days. • 21 women are equal to 14 men. (21*2/3) • 21*8/6*15/14 = 30 days. Ans. www.afterschoool.tk

A can do a work in 20 days, and B can do it in 24 days. B worked for 6 days on this work and left. Now A will complete the remaining work – how much time will he take? • B’s one days work: 1/24. • 6 days work: 6*1/24 = ¼ • Remaining work = 1- ¼ = ¾ • A completes the whole work in 20 days, he will complete ¾ work in 20* 3/4 days - = 15 Days. Ans. www.afterschoool.tk

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