John went to the Hospital at the speed of 60 km per hour while returning for his home he covered the half of the distance at the speed of 10 per hour, but suddenly he realized that he was getting late so he increased the speed and reached the home by covering rest 1/2 of the distance at the speed of 30km per hour. The average speed of the John in the whole length of journey is?
Choose the correct option:
A) 18 km/hr	B) 20 km/hr	C) 24 km/hr	D) 28 km/hr	E) 32 km/hr
Let distance between his home and hospital =   d   d km   Total distance travelled   =   d   +   d   =   2   d   =d+d=2d km   Total time taken   =   d   60   +   (   d   2   )   10   +   (   d   2   )   30   =d60+(d2)10+(d2)30   =   d   60   +   d   20   +   d   60   =   5   d   60   =   d   12   =d60+d20+d60=5d60=d12 hr   Average speed in the whole journey   =   2   d   (   d   12   )   =   2   d   ×   12   d   =   24   =2d(d12)=2d×12d=24 km/hr   24 km/hr
<result>C</result>
John went to the Hospital at the speed of 60 km per hour while returning for his home he covered the half of the distance at the speed of 10 per hour, but suddenly he realized that he was getting late so he increased the speed and reached the home by covering rest 1/2 of the distance at the speed of 30km per hour. The average speed of the John in the whole length of journey is?