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
Explanation:
Let total number of black balls be 100b and total number of white balls be 100w. ∴ 100w + 100b = 450 ⇒ w + b = 4.5 …(1)
According to the question. Number of metallic balls: White metallic = 40% of 100w = 40w Black metallic = 50% of 100b = 50b
Now, 40w = 50b ⇒ w = 1.25b …(2)
From (1) and (2) 1.25b + b = 4.5 ⇒ b = 2 and w – 2.5
∴ Number of non-metallic white balls = 60% of 100w = 150 and, number of non-metallic black balls = 50% of 100b = 100
∴ Total number of non-metallic balls = 150 + 100 = 250
Hence, 250.
Help us build a Free and Comprehensive Preparation portal for various competitive exams by providing us your valuable feedback about Apti4All and how it can be improved.