Question

The ratio of copper and zinc in an alloy is 9:5. If the weight of zinc in the alloy is 9.5gm, then the weight of copper in it is…………..
A. 17.2gm
B. 17.1gm
C. 17.5gm
D. 17.4gm

Answer 1

Hint – In order to get the right option in as the answer you need to assume the variable as the weight of copper and equate the ratio of their mixture as the ratio of their weight. Doing this will solve this problem and will provide you the right answer.

Complete step by step solution:
The ratio of weight of copper and zinc is given as: 9:5
Let the weight of the copper be x and the weight of the zinc is given as 9.5gm.
So, we can do $\dfrac{{\text{9}}}{{\text{5}}}{\text{ = }}\dfrac{{\text{x}}}{{{\text{9}}{\text{.5}}}}$.
So we can get the value of x as $x={9.5\times{\dfrac{9}{5}}}= 9.5 \times 1.8 = 17.1$
Hence the answer to this problem will be 17.1gm
So, the correct option is B.

Note – To get such a problem solved in which we are provided a ratio we have to always try to assume the variables and equate the respective terms with the ratio since ratio is directly or inversely proportional to the respective terms if we are measuring different quantities. Here it is directly proportional because the ratio provided us is the ratio of proportion of the alloy and it is directly proportional to the weight of the metal. Knowing and recognizing these things in such problems will provide you the right answer.