Correct option is D
Let the amount received by P, Q, and R be 4x, 7x and 9x respectively.
And the amount received by S = (4x+7x+9x)/5=4x
ATQ,
(7x+9x)-(4x+4x)=1800
8x=1800
x=225
Required average amount = (4x+9x)/2 = 6.5x
=6.5×225 =Rs 1462.5