Question

On selling a boat for rs 521 a man gains 8 %; for how much should he sell it to gain 9%

Answer 1

CP of the boat on profit 8%is 
521-[8/100* 521]
521-41.68
479.32
thus the sp of the boat on 9% profit is 
479.32+[9/100*479.32]
479.32+43.1388
522.4588
so the SP on 9% gain is 522.4588

Answer 2

S.P. of the boat = Rs 521
Gain % = 8 %
Gain = Rs(8/100 × 521) = Rs 4168/100 =Rs 41.68
C.P. = (S.P. - Gain)
        = Rs( 521-41.68) = Rs 479.32

Gain % to be made= 9 %
C.P.= Rs 479.32

If C.P. is Rs 100 then S.P. is Rs 109
If C.P. is Rs 1 then S.P. is Rs 109/100

If C.P. is Rs 479.32 then S.P. is Rs (109/100)×(47932/100) = Rs 5224588/10000                                                                                            =Rs 522.4588

To make a profit of 9 % the boat must be sold at Rs 522.4588