Ira has to reach Nagpur which is 744 km away in 16 hours. His starting speed for 8 hours was 34 km/hr. For the next 87 km his speed was 29km/hr. By what speed he must travel now so as to reach Nagpur in decided time of 16hours?

Correct option is C

Given:

Distance to Nagpur = 744 km

Total time = 16 hours

Speed for first 8 hours = 34 km/hr

Distance for next part = 87 km

Speed for next part = 29 km/hr

Formula used:

Time = $$\frac{\text{Distance }}{\text{ Speed}}$$​​

Solution:

Distance covered in first part = Speed × Time = 34 × 8 = 272 km

Distance covered in second part = 87 km

Distance covered in third part = Total Distance - (Distance covered in first + Distance covered in second)
= 744 - (272 + 87)
= 744 - 359
= 385 km

Time taken for first part = $$\frac{\text{Distance }}{\text{ Speed}}$$​ =$$\frac{272 }{ 34}$$​ = 8 hours

Time taken for second part =$$\frac{\text{Distance }}{\text{ Speed}}$$​ = $$\frac{87 }{ 29}$$= 3 hours

Time left for third part = Total time - (Time for first + Time for second)
Time left for third part = 16 - (8 + 3) = 16 - 11 = 5 hours

Speed for third part = $$\frac{\text{Distance }}{\text{ Speed}}$$​​
Speed for third part =$$\frac{385 } 5$$​= 77 km/hr