Question

Pankaj went to the post-office at the speed of 60 km/hr. While returning to his home, he covered half of the distance at the speed of 10 km/hr, but suddenly he realized that he was getting late so he increased the speed and reached the home by covering rest half of the distance at the speed of 30 km/hr. The average speed of the Pankaj in the whole length of journey is :

• A. 5.67 km/hr
• B. 24 km/hr
• C. 22.88 km/hr
• D. 5.45 km/hr

Answer 1

The correct option is B 24 km/hr

Average speed when Pankaj was returning
$=\frac{2\times 10\times 30}{40}=15km/hr$
Now the average speed of the whole journey
$=\frac{2\times 15\times 60}{75}=24km/hr$