Question

In a 5/6 pound mixture of sand and gravel, 1/4 pound is gravel.

Answer 1

Total mass of mixture is given as 5/6 pound, in which 1/4 pound is gravel. Amount of sand in the mixture will be 5/6 - 1/4 = 7/12 So, the ratio of sand to that of gravel in given mixture is 7/12:1/4 = 7:3. i.e every 10 parts of mixture contain 7 parts of sand and 3 parts of gravel. If we are given 1-pound of same mixture, it will contain 1 * 3/10 pound gravel, i.e. 0.3 pound.

Answer 2

1/4lbs of gravel is in 5/6lbs of mixture
xlbs of gravel is in 1lbs of mixture
1/4:5/6=x:1, 1/4*1=5/6*x
5/6*x=1/4, x=(1/4)/(5/6)
x=3/10
In 1 pound of mixture of sand and gravel, 3/10 pound is gravel.