md + m′d′ + m″d″ + m‴d‴
S = D.
Example.—Let column 1 show the partial amounts in cubic yards. Column 2 the corresponding hauls.
| 1,000 | × 200 = | 200,000 |
| 2,000 | × 300 = | 600,000 |
| 5,000 | × 400 = | 2,000,000 |
| 8,000 | × 600 = | 4,800,000 |
| 16,000 | 7,600,000 |
and 7,600,000
16,000 = 475 feet average haul.
Proof.—Assume the cost of moving 1,000 yards one foot as ten cents, the costs of the separate masses are
| 1,000 yards 200 feet is | $20.00 |
| 2,000 yards 300 feet is | 60.00 |
| 5,000 yards 400 feet is | 200.00 |
| 8,000 yards 600 feet is | 480.00 |
| Sum, | $760.00 |
also the cost of moving 16,000 yards 475 feet is
16 × 475 × 10 = $760.00.
119. The movement of earth is effected by shovels, barrows, horses and carts, or by cars. In round numbers we can move earth
| By shovels alone | 10 to | 20 feet, |
| By barrows alone | 20 to | 100 feet, |
| By carts | 100 to | 500 feet, |
| By cars | 500 to | 5,000 feet, |