Problem Solving

Que: To make a certain color, a paint dealer mixes 3.4 liters of red color to a base that is 68 liters. The paint manufacturer recommends mixing 0.7 liters per 10 liters of the base to make that color. By what percent should the mixing be increased to bring it to the recommendation?

(A) 10%
(B) 33.33%
(C) 40%
(D) 66.66%
(E) 72%

Solution: The mixing for 68 liters of the base was 3.4 liters of red color.

The recommended mixing for every 10 liters of the base was 0.7 liters of red color.

Thus, as per the recommendation, the amount of red color required for 68 liters of base = \(\frac{0.7}{10}\cdot68\) = 4.76 liters

Percent change: \(\frac{\left(After\ -\ Before\right)}{Before}\cdot100\left(\%\right)\) [After: 4.76 ; Before: 3.4]

=> \(\frac{\left(4.76\ -\ 3.4\right)}{3.4}\cdot100\left(\%\right)\)

=> \(\frac{1.36}{3.4}\cdot100\left(\%\right)\) = 40%

Therefore, C is the correct answer.

Answer C