### 7. Ratio and Proportion - intmath.com

Mar 21, 2018· Concrete is a mixture of gravel, sand and cement, usually in the ratio `3:2:1`. We can see that there are 3 + 2 + 1 = 6 items altogether. As fractions, the amount of each component of the concrete is: Gravel: `3/6=1/2` Sand: `2/6=1/3` Cement: `1/6` Example 3. One of the most famous ratios is the ratio of the circumference of a circle to its ...