Question

A boat goes 16 km upstream and 24 km downstream in 6 hours. It can go 12 km upstream and 36 km downstream in the same time. Based on the above information, answer the following questions: ( ) 21. Speed of boat in still water is 1 point 12 km/h 10 km/h 8 km/h 6 km/h Clear selection 22. Speed of river is 1 point 2 km/h 4 km/h 6 km/h 8 km/h Clear selection 23. Speed of boat in downstream is 1 point 12 km/h 10 km/h 8 km/h 16 km/h 24. Speed of boat in upstream is 1 point 12 km/h 10 km/h 8 km/h 4 km/h 25. Time taken by boat is going 6 km down and 4 km up is 1 point 4 h 3 h 2 h 1.5 h​

Answer 1

Answer:

Let speed of the boat in still water = x km/hr, and

Speed of the current = y km/hr

Downstream speed = (x+y) km/hr

Upstream speed = (x - y) km/hr

... (1)

... (2)

Putting begin mathsize 12px style fraction numerator 1 over denominator straight x plus straight y end fraction equals straight u space space and space space fraction numerator begin display style 1 end style over denominator begin display style straight x minus straight y end style end fraction equals straight v end style  the equations become:

24u + 16v = 6

Or, 12u + 8v = 3... (3)

36u + 12v = 6

Or, 6u + 2v = 1... (4)

Multiplying (4) by 4, we get,

24u + 8v = 4… (5)

Subtracting (3) by (5), we get,

12u = 1

u = begin mathsize 12px style 1 over 12 end style

Putting the value of u in (4), we get, v = begin mathsize 12px style 1 fourth end style

Thus, speed of the boat upstream = 4 km/hr

Speed of the boat downstream = 12 km/hr

Step-by-step explanation: