Mixture

[Guest]

Calculate pounds of sand added to 50 pounds of a cement-sand mixture which is 40% sand to make the resulting mixture 60% sand.

Thanks for your assistance.

[Guest]

Mix now is 50 pounds...so contains 20 pounds sand as it has a 40% sand mix.....20 = 0.4 x 50.....

Let the amount we need to add be "z"
Then

20 + z = 0,6 ( 50 + z ) .....because new mix is 60%

20 + z = 30 + 0.6

0.4 z = 10

z = 25 pounds sand added

Now total mix is 50 + 25 = 75 pounds
and contains sand 20 + 25 = 45 pounds sand

45 / 75 = 0.6 = 60% sand in mix

simple