Question

15. Before oil is added to a certain road surface material, the other ingredients are mixed. The mixture contains

45% 3/4 inch stone and 32% % inch stone. The balance of the mixture is made up of sand. If the mixture weighs
15,000 pounds before the oil is added, how many pounds of each ingredient are in the mixture?

Answer 1

sand = 3450 pounds

3/4 inch stones =6750 pounds

1 inch stones =4800 pounds.

Explanation:

The mixture composition is :

45% three-quarter inch stones

32% inch stones and

sand for balance

The percent here is by mass of material used.

Weight of mixture is 15,000 pounds before oil addition.

Use the percent by weight for the two types of stones and calculate real values in pounds

Formula to apply is:

Mass percent = (mass of a material/ total mass of mixture) * 100

For 3/4 inch stones it will be:

`0.45= (x)/(15000) *100\\\\0.45=(x)/(150) \\0.45*150=x\\x=6750`

The 3/4 inch stones weigh 6750 pounds

The 1 inch stones will be

`32/100 * 15000 =4800`

The 1 inch stones weigh = 4800 pounds

Total for the two items : 4800+6750 =11550 pounds

The sand used weighs : 15000 - 11550 = 3450 pounds