Question

A boat can row 1 km with stream in 10 mins . and 1 km against stream in 20 mins. what is the speed of the boat in still water

Answer 1

Answer:

⇝ 4.5km/hr ✔

Explanation:

⇝Given

• Distance in upstream and downstream = 1 km
• Downstream time= 10 min = 10/60 hour = 1/6 h
• Upstream time = 20 min = 20/60 hour = 1/3 h

⇝Now,

$\large\bold{ \tt{Downstream\: speed \: = \: \red{ \frac{1}{ \frac{1}{6} } = 6 \pink{ km/h}}}}$

$\large\bold{ \tt{Upstream\: speed \: = \: \red{ \frac{1}{ \frac{1}{6} } = 3 \pink{ km/h}}}}$

⇝speed of boat in still water

$\large\bold{ \tt{ \: \: \: = \: \red{ \frac{1}{2} \times ( \green{speed \: downstream \: \pink+ \:speed \: upstream } )}}}$

$\large \bold{\tt{ = \purple{ \frac{1}{2} \times (6 + 3) }= \blue{\frac{1}{2} \times 9 =} \pink{ 4.5km/h}}}$

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