CAT Exam 2021 Slot 2 Solved Paper

Question : 60 of 66

Marks: +1, -0

A box has 450 balls, each either white or black, there being as many metallic white balls as metallic black balls. If 40% of the white balls and 50% of the black balls are metallic, then the number of non-metallic balls in the box is

Your Answer:

Validate

Solution:

Let the number of white balls be

x

and black balls be

y

So we get

x+y = 450

...(1)

Now metallic black balls

= 0.5 y

Metallic white balls

= 0.4 x

From condition

0.4x=0.5 y

we get

4 x- 5 y=0

...(2)

Solving (1) and (2) we get

x=250

and

y =200

Now number of Non Metallic balls

= 0.6 x+0.5 y = 150+100 = 250

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