Two copiers are used to produce 2400 copies of a document.

Since both copiers must finish at the same time, the work they do must be proportional to their speeds. If the slower copier has speed s, the faster has speed 1.5s. In equal time t, the slower copier completes s·t work and the faster completes 1.5s·t work. Their work ratio is 1:1.5, so the faster copier must produce 1.5/(1+1.5) × 2400 = 1.5/2.5 × 2400 = 1440 copies.

Step-by-step Derivation:
Let the speed of the slower copier = s copies per unit time. Speed of faster copier = 1.5s copies per unit time.

For both to finish in the same time t:

• Copies by slower copier = s × t
• Copies by faster copier = 1.5s × t

Total copies: s·t + 1.5s·t = 2400
2.5s·t = 2400
s·t = 960

Therefore:

• Slower copier produces: s·t = 960 copies
• Faster copier produces: 1.5s·t = 1.5 × 960 = 1440 copies

Verification: 960 + 1440 = 2400 ✓