# If you mixed 80 tons of sand, 12 tons of rock, and 4.0 tons of cement to make concrete, what would the percent by weight of sand be?

Aug 29, 2016

The percent by mass would be 83 %.

#### Explanation:

The mass percent of a component in a mixture is given by the formula

color(blue)(|bar(ul(color(white)(a/a) "Mass Percent" = "Mass of component"/"Mass of mixture" × 100 % color(white)(a/a)|)))" "

$\text{Mass of sand = 80 T}$
$\text{Mass of mixture" = "mass of sand + mass of rock + mass of cement" = "80 T + 12 T + 4 T" = "96 T}$
"Mass percent of sand" = ( 80 color(red)(cancel(color(black)("T"))))/(96 color(red)(cancel(color(black)("T")))) × 100 % = 83 %