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A and B are two alloys formed by the combination of gold and copper in the ratio 5 : 3 and 5 : 11 respectively. Equal quantities of these two alloys a
Question

A and B are two alloys formed by the combination of gold and copper in the ratio 5 : 3 and 5 : 11 respectively. Equal quantities of these two alloys are melted and mixed to form a new alloy C. Now, alloy C contains gold and copper in the ratio:

A.

33 : 25

B.

15 : 17

C.

17 : 15

D.

25 : 23

Correct option is B

Given:

Alloy A is formed by the combination of gold and copper in the ratio 5:3.

Alloy B is formed by the combination of gold and copper in the ratio 5:11.

Equal quantities of alloys A and B are melted and mixed to form a new alloy C.

Solution:

Gold in alloy A: 58\frac{5}{8}​ of the total quantity (since 5 parts out of 8 are gold).

Copper in alloy A:38 \frac{3}{8}​ of the total quantity.

Gold in alloy B:516 \frac{5}{16} ​of the total quantity (since 5 parts out of 16 are gold).

Copper in alloy B: 1116 \frac{11}{16}​ of the total quantity.

Let the equal quantity of alloys A and B used in the mixture be x.

Gold in A =58×x \frac{5}{8} \times x

Copper in A =38×x \frac{3}{8} \times x

Gold in B = 516×x \frac{5}{16} \times x

Copper in B =1116×x \frac{11}{16} \times x

Total Gold in Alloy C:

Total Gold = 58x+516x=1016x+516x=1516x\frac{5}{8}x + \frac{5}{16}x = \frac{10}{16}x + \frac{5}{16}x = \frac{15}{16}x

Total Copper in Alloy C:

Total Copper = 38x+1116x=616x+1116x=1716x\frac{3}{8}x + \frac{11}{16}x = \frac{6}{16}x + \frac{11}{16}x = \frac{17}{16}x​​

Ratio of Gold to Copper =1516x1716x=1517 \frac{\frac{15}{16}x}{\frac{17}{16}x} = \frac{15}{17}

The ratio of gold to copper in alloy C is 15:17.

Alternate Method:


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