Maths 25 May

MATHS 10 wonderful questions Dr. T.K. Jain. AFTERSCHOOOL M: 9414430763 [email protected] www.afterschool.tk www.afterschoool.tk

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A B C D E are playing a game of cards, A says to B if you give me three cards, you will have as many as E has and if I give you three cards, you will have as many as D has. A & B together have 10 cards more thatn what D & E together have. If B has two cards more than what C has and the total number of cards is 133, how many cards does B have?

• Convert all these into B:1).B-3 =E, (2)B+3=D(3)A+B-10=D+E(4)B-2=C • 5)A+B+C+D+E=133; A=D+E-B+10 (from3); 5 modified: B+3+B-3B+10+B+B-2+B+3+B-3=133.: 7B+8=133; 7B=125; B=125/7 = 18 approx. www.afterschoool.tk

There are some cows, bulls and 45 hens in a group. One caretaker looks after 15 animals. The number of bulls is twice the number of cows. If the number of heads is less than the total number of feet by 186 (including caretakers) how many caretakers are there? Options: 6,8,9

• Let the no of cows = x;, let is take no of feet: 4(x+2x)+2(45+(x+2x+45)/15) • No. of Heads =(x+2x+45)+ (x+2x+45)/15) to equate them - add 186 in second. • Let the caretakers by 6, so x+2x=45;x=15; so 180+102=186+90+6 • 282=282 – so option 6 is right. www.afterschoool.tk

If 2^32 +1 is exactly divisible by 641, which of the following is divisible by 641? (a) 2^96 +1 (b) 2^16 +1? • Observe the pattern in the power of 2. You will notice a pattern, for example, 2^2 +1, 2^6 +1 , 2^18+1 are all divisible by 5 –2^3 +1, 2^9 +1 , 2^27+1 are all divisible by 3 similar pattern exists here – so the number divisible is 2^96 +1 ans.

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When 40% of a number is added to 42, the result is the number itself. What is the number? ..40X+42=X;.40X-X=-42;, (x-.40x = .60x); , .6X=42;, X=42/.6(multiply both by 10) X=420/6= 70Ans. www.afterschoool.tk

The population of a village is 5000 and it increases @ 2% every year. Afer 2 years, the population will be? • 5000*1.02*1.02 = 5202 ans.

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The numerator of a fraction is doubled and the denominator is increased by 3, the new fraction is 3/5. what is the original fraction is the denominator is more than twice the numerator by 1?

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Let us assume numerator to be x Denominator is 2x+1 Double x 2x/3+(2x+1) = 3/5 ; 2x/2x+4 =3/5; 10x =6x+12; 4x=12; x = 3; so fraction = 3/7 ans. www.afterschoool.tk

Ratio of Zinc and copper in a brass piece is 13:7. how much zinc will be there in 100 kg. of such a piece?

• Zinc will be 65 kg. • 13/ 20 *100.

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Rs. 1360 is divided among ABC A gets 2/3 of B, B gets ¼ of C, what is share of B? • Lets take LCM of 3 &4; 12. let us assume C got 12. B got 3, A got 2. ratio is 2:3:12. share of B : 3/17 (1360) = 240 Ans.

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94 is divided in two parts. Fifth part of the first and eighth part of second are in the ratio 3:4. What is the first part?

• The first part is 3*5 = 15, second is 4*8 =32, first part is : 15/47 (94) • First is 30Ans.

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