hi,,

My approach is a below.

assume the child mug is onelitre large.

The company's apple drink is one litre and the other drink is 1 litre

Now when the child pours the 3/4 cup of the juice it's 750 ml.
=> (750/1000)*5 is the juice content. i.e. 37.5 ml of pure juice

now the other juice has 50% => 1/4 contributes 125 ml of pure juice.

Now the total pure juice in the solution is 125+37.5 ml

=> the total percentage in the mug is (163.5/1000)*100 =>

16.3%

[/quote]

Let the total capacity of the cup be 100 units
3/4 of the cup has juice with 5% apple juice, so 75 units and 5% in that is 3.75
1/4 of the cup has juice with 50% apple juice, so 25 units and 50% in that is 12.5

So overall % of apple juice in the mixture = 12.5+3.75 = 16.25 ~= 16.3%

IMO B.