V=50*5.625/1.1+55*5.625/1.1^2+54*5.625/1.1^3+52*5.625/1.1^4+51*5.625/1.1^5+50*5.625/0.1/1.1^5=5.625(50/1.1+55/1.21+54/1.331+52/1.464+51/1.611+500/1.611)
=5.625*509=2863
妳也不幫我算,懶!