Q.1) An alloy consists of 27 1/2 kg of copper and 2 1/2 kg of tin. Find the ratio by weight of tin to alloy.
Q2) Karim secured 35 marks out of 50 in English and 29 marks out of 40 in Science. In which subject he perfomed better?
Q.3) Three children are aged 2 yrs, 3 yrs and 4 yrs respectively. Devide Rs.90 among them in the ratio of their ages.
Q.4) Devide Rs.810 into 3 parts in the ratio 1/4:2/5:1 3/8.
Q.5) If A:B= 4:5 and B:C= 9:13, find A:C.
Q.6) If A:C= 2:3 and B:C= 5:6, find A:B.

2

Answers

The Brainliest Answer!
2014-08-27T11:36:54+05:30
1) 27 1/2 = 55/2
2 1/2 = 5/2
55/2 : 5/2
55 : 5
11 ; 1
The ratio of tin to alloy is 1 : 11
2) We can do this by finding percentage:
35/50 * 100
= 70%
29/40 * 100
= 72.5%
Karim performed better in Science.
3) Sum of the ratios = 2 + 3 + 4 = 9
2 yr old share = 2/9 * 90 = Rs 20
3 yr old share = 3/9 * 90 = Rs 30
4 yr old share = 4/9 * 90 = Rs 40
4) 1/4 : 2/5 : 11/8
LCM = 40
10/40 : 16/40 : 55/40
10 : 16 : 55
Sum of the Ratios = 10 + 16 + 55 = 81
10/81 * 810 = Rs 100
16/81 * 810 = Rs 160
55/81 * 810 = Rs 550
5) A:B = 4:5 
B:C = 9:13
A/B = 4/5 - (1)
B/C = 9/13
B = 9/13 * C
For - (1) Substitute the value for B
A / 9/13 * C = 4/5
A/C = 4/5 * 9/13
      = 36/65
A:C = 36 : 65
6) A:C = 2:3
B:C = 5:6
A/C = 2/3 - (1)
B/C = 5/6
C = 5/6 * B
For - (1) Substitute the value for C
A / 5/6 * B = 2/3
A/B = 2/3 * 5/6
10/18 = 5/9
A:B = 5 : 9
2 5 2
If it was useful please mark as best
2014-08-27T13:26:12+05:30

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1)  Ratio by weight of Tin to Alloy =
     \\ 2\frac{1}{2} : [\ 27\frac{1}{2} + 2\frac{1}{2}\ ] = \frac{\frac{5}{2}}{30} =\ \frac{5}{2*30} = \frac{5}{60}\ =\ 1\ :\ 12\ \\

2) Ratio of marks in English = 35/50 = 7/10
    Ratio of marks in Science = 29/40

   Ratio of marks in Science - Ratio of marks in English =
               \frac{29}{40} - \frac{7}{10} = \frac{29 - 7 * 4}{40} = \frac{1}{40} \\
   So Marks in Science are more. He performed better in Science.

3) Divide Rs 90 by the ratio 2 : 3 : 4
   The first child gets an amount = Rs 90\ *\ \frac{ 2 }{2+3+4} = Rs 90\ *\ \frac{2}{9} =\ Rs\ 20 \\
   The second child gets an amount = Rs 90*\frac{3}{2+3+4} = Rs 90*\frac{3}{9} =Rs\ 30\\
   The third child gets an amount = Rs 90\ *\ \frac{ 4 }{2+3+4} = Rs 90\ *\ \frac{4}{9} =\ Rs\ 40 \\

4)

  Divide\ Rs\ 810\ in\ ratios\ = \frac{1}{4} : \frac{2}{5} : 1\frac{3}{8} \\ \\ \ \ \ \ Ratios\ \frac{1}{4} : \frac{2}{5} : \frac{8+3}{8} =  \frac{1}{4} : \frac{2}{5} : \frac{11}{8} \\ \\ \ \ \ \ Sum\ of\ ratios\ =\ \frac{10 + 2*8 + 11*5}{8*5} = \frac{81}{40} \\ \\


Part\ 1\ :\ Rs\ 810\ * \frac{\frac{1}{4}}{\frac{81}{40}} = Rs\ \frac{810 * 40}{81 * 4} = Rs\ 100 \\ \\  Part\ 2\ :\ Rs\ 810\ * \frac{\frac{2}{5}}{\frac{81}{40}} = Rs\ \frac{810 * 40 * 2}{81 * 5} = Rs\ 160 \\ \\  Part\ 3\ :\ Rs\ 810\ * \frac{\frac{11}{8}}{\frac{81}{40}} = Rs\ \frac{810 * 11 * 40}{81 * 8} = Rs\ 550 \\ \\

5) A : B = 4 : 5 and B: C = 9 : 13

   \frac{A}{B} = \frac{4}{5} \ \ \ \ \ \ \ \frac{B}{C} = \frac{9}{13} \\ \\ Multiply\ the\ two\ ratios.\\ \\ \frac{A}{B} * \frac{B}{C} = \frac{4}{5} * \frac{9}{13} \\ \\ \frac{A}{C} = {4*9}{5*13} = \frac{36}{65} \\ \\ A: C = 36 : 65 \\ \\

6) A:C = 2 : 3    B  : C = 5 : 6

    \frac{A}{C} = \frac{2}{3} \ \ \ \ \ \ \ \frac{B}{C} = \frac{5}{6} \\ \\ Divide\ the\ first\ fraction\ by\ the\ second\ fraction: \\ \\ \frac{\frac{A}{C}}{\frac{B}{C}} = \frac{\frac{2}{3}}{\frac{5}{6}} \\ \\ \frac{A*C}{C*B} = \frac{2*6}{3*5} \\ \\ \frac{A}{B} = \frac{4}{5} \\ \\ A : B = 4 : 5 \\


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