question_answer

In two types of stainless steel, the ratio of chromium and steel are 2: 11 and 5: 21, respectively. In what proportion should the two types be mixed, so that the ratio of chromium to steel in the mixed type become 7: 32?

[SSC (10+2) 2017].

A) 1 : 2     

B) 1 : 3

C) 2 : 3                             

D) 3 : 4

Correct Answer: A

Solution :

Ratio of chromium in type I steel \[=\frac{2}{13}\]

Ratio of chromium in type II steel \[=\frac{5}{26}\]

Ratio of chromium in mixed steel \[=\frac{7}{39}\]

The required ratio

So, the required ratio \[=\,\,\,\frac{\frac{1}{78}}{\frac{1}{39}}\,\,=\,\,1:2\]