If the speed of boat in still water on Saturday was 27 km/hr and the speed of boat in still water on Wednesday was $$66\dfrac{2}{3}\%$$ more than that of Saturday and time taken to travel upstream on Wednesday is $$\dfrac{16}{13}$$ times than time taken by it to travel downstream on Saturday, then find the speed of stream (in kmph) on Saturday?

Distance upstream (Wednesday): 12% of 4800 km = 576 km.

The speed of the boat in still water (Wednesday) is 66.67% which is 2/3 more than on Saturday: $$27\times\left(1+\dfrac{2}{3}\right)=45\ kmph$$

Upstream speed (Wednesday) = Speed of boat - Speed of stream = 45 − 6 = 39 kmph

Time taken upstream (Wednesday) =  $$\dfrac{576}{39\ }=\dfrac{192}{39}\ hrs$$

We are given that the upstream time on Wednesday is 16/13 times the downstream time on Saturday.

$$\dfrac{192}{13}=\dfrac{16}{13}\times Downstream\ Time$$

So, downstream time: 12 hours

Downstream speed (Saturday): 432/12 = 36 kmph

Since the downstream speed is the sum of the boat's speed in still water and the stream's speed.

36 kmph = 27 kmph+Speed of stream

Speed of stream (Saturday): 36−27 = 9 kmph