Answer:
200 kg of sand; 600 kg of gravel; 800 kg of cement
Explanation:
sand : gravel : cement = 1 : 3 : 4
If we multiply each number in the ratio by 10, we get:
10 + 30 + 40 = 80
That is too small since we want a sum of 1600.
What number do we multiply each number in the ratio by to get a sum of 1600? Let's call that number x.
1x + 3x + 4x = 1600
8x = 1600
x = 200
We need a factor of 20 for the numbers in the ratio.
200 × 1 = 200
200 × 3 = 600
200 × 4 = 800
Check: 200 + 600 + 800 = 1600
Answer: 200 kg of sand; 600 kg of gravel; 800 kg of cement