Shyam drives his car 30 km at a speed of 45 km/h and, for the next 1 h 20 m, he drives it at a speed of 51 km/h. Find his average speed (in km/h) for the entire journey.

49

Shyam drives is 30 km at a speed of 45 km/h

And 45 km/h in 60 min

So , Shyam can go 3 km in 4 min

He go 30 km in 40 min

for the next 1 h 20 m, he drives it at a speed of 51 km/h

1 h 20 min = \(\frac{4}{3}\) hours

Distance traveled in \(\frac{4}{3}\) hours  with speed 51 km/h ,

= 51 × \(\frac{4}{3}\) hours  = 68 km

Total distance = 30 + 68 = 98 km

Total Time = 40 min +  1hr 20 min = 2 hours

Average speed = \(\frac{98}{2}\)  = 49 km