Posted by Nick on .
A jar contains red, blue and yellow marbles.The number of red marbles is ten more than the number of yellow marbles and the number of blue marbles is double the number of yellow marbles. If the probability of choosing a yellow marble is onefifth , how many marbles are in the jar?

Algebra 
Reiny,
yellow marbles  x
blue marbles  2x
red marbles  x+10
total = 4x + 10
prob to choose a yellow = x/(4x+10) = 1/5
5x = 4x+10
x = 10
10 yellows , 20 blues, and 20 reds for a total of 50 marbles