Question

A man completes 30km of a journey at 6 km/hr and the remaining 40km of the journey in 5 hours. his average speed for the whole journey is .

Answer 1

the time in first journey =5
the average speed =30+40/5+5
70/10
=7

Answer 2

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A man completes 30km of a journey at 6 km/hr and the remaining 40km of the journey in 5 hours. his average speed for the whole journey is ?

${ \bf{ \red \dagger{ \underline{ \underline{Solution} }}} \red\dagger}$

• A man completes 30km of a journey at 6 km/hr .

Distance = 30 km

Speed = 6 km/hr

Time taken by man to cover 30 km = ?

Now we use formula

${ \bf{ \red \dashrightarrow{ \sf\pink{Speed \: = \frac{Distance}{Time} }}}}$

${ \bf{ \red \dashrightarrow{ \sf\pink{6 \: = \frac{30}{Time} }}}}$

${ \bf{ \red \dashrightarrow{ \sf\pink{Time \: = \frac{30}{6} }}}}$

${ \bf{ \red \dashrightarrow{ \sf\pink{Time \: = 5 \: hour}}}}$

Time taken by man to cover 30 km is 5 hour.

• A man completes 40km of a journey at 5 hr .

Distance = 40 km

Time taken by man to cover 40 km

= 5 hour

Speed = ?

${ \bf{ \red \dashrightarrow{ \sf\pink{Speed \: = \frac{Distance}{Time} }}}}$

${ \bf{ \red \dashrightarrow{ \sf\pink{Speed \: = \frac{40}{5} }}}}$

${ \bf{ \red \dashrightarrow{ \sf\pink{Speed \: = 8 \: km/hr }}}}$

Man cover 40 km in at speed 8 km/hr.

${ \bf{ \red \dashrightarrow{ \sf\pink{Average \: speed \: = \frac{Total \: distance }{Total \: time } }}}}$

${ \bf{ \red \dashrightarrow{ \sf\pink{Average \: speed \: = \frac{ 30 + 40 }{5 + 5 } }}}}$

${ \bf{ \red \dashrightarrow{ \sf\pink{Average \: speed \: = \frac{70 }{10 } }}}}$

${ \bf{ \red \dashrightarrow{ \sf\pink{Average \: speed \: = 7 \: km/hr }}}}$

Hence, average speed of man for the whole journey is 7 km/hr.