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# The number of telephone call N between two cities A and B varies directly as the...

### Question

The number of telephone call N between two cities A and B varies directly as the population PA, PB in A and B respectively and inversely as the square of the distance D between A and B. Which of the following equations represents this relation?

### Options

A) $$N = \cfrac{kP_A}{D^2} + \cfrac{CP_B}{D^2}$$

B) $$N = \cfrac{kP_AP_B}{D^2}$$

C) $$N = kDP_AP_B$$

D) $$N = kDP_A + CDP_B$$

E) $$N = kD^2P_AP_B$$