Question

A driver travels 10 Km in 15 minutes, stops for a 15-minute break, then travels an additional 60 Km in 45 minutes.
1. Calculate his average speed for
a. The first 15 minutes of his journey
b. The last 45 minutes of his journey
c. The entire journey.

Answer 1

Given :

In first 15 minutes ( 1/4 hour ) , distance traveled by driver = 10 km

In last 45 minutes ( 3/4 hour ),  distance traveled by driver = 60 km

To find :

Average speed for -

(a). The first 15 minutes of journey .

(b). The last 45 minutes of journey .

(c). The entire journey.

Solution :

(a). Average speed in first 15 minute ( 1/4 hour ) of journey =  10 / (1/4) km/h

                                                                                                 = 40 km/h

(b).  Average speed in last 45 minute ( 3/4 hour ) of journey = 60 / (3/4) km/h

                                                                                                   = 80 km/h

(c). Average speed in entire journey = 70 / (5/4) km/h

                                                            = 56 km/h

Average speed for -

(a). The first 15 minutes of journey  is 40 km/h .

(b). The last 45 minutes of journey  is 80 km/h .

(c). The entire journey is 56 km/h .