Question

How many grams of a 10% cream must be mixed with a 2% cream to prepare 60 grams of a 5% cream? A. 225 g. B. 12 g. C. 15 g. D. 27 g

Answer 1

In my opinion is B 12g 

Answer 2

22.5 g

Step-by-step explanation:

Let

x = mass of the 10% (0.1) cream

y = mass of the 2% (0.02) cream

We mix x grams of the 10% cream with y grams of the 2% cream to obtain 60 grams of a 5% (0.05) cream.

0.1 x + 0.02 y = 0.05 × 60

0.1 x + 0.02 y = 3 [1]

The sum of x grams and y grams is 60 grams.

x + y = 60

y = 60 - x [2]

We replace [2] in [1]

0.1 x + 0.02 (60 - x) = 3

0.1 x + 1.2 - 0.02 x = 3

0.08 x = 1.8

x = 22.5 g

I think there is a typo in the option A, because the correct answer is that you need 22.5 g of the 10% cream.

Yo can get the mass of the 2% cream by replacing this value in [2].

y = 60 - x = 60 - 22.5 = 37.5