Question 1162518
<br>
Here a solution by a quick and easy method for solving "mixture" problems like this if a formal algebraic solution is not required.<br>
You are mixing 25% and 50% to obtain 40%:<br>
(1) 40% is 3/5 of the way from 25% to 50%.  (Picture the three percentages on a number line; 25 to 50 is a difference of 25; 25 to 40 is a difference of 15; 15/25 = 3/5.)
(2) That means 3/5 of the mixture has to be the higher percentage ingredient.<br>
ANSWER: 3/5 of 5kg, or 3kg, of 50% silver; the other 2kg of 25% silver.<br>
CHECK:
.50(3)+.25(2) = 1.5+.5 = 2
.40(5) = 2<br>