Question

ix) A motorist covers first 50 km of his journey at a speed of 40 km/hr and the remaining 70 km at a speed of 60 k /hr. Find:

a) The total time taken to complete the journey

b) His average speed

​

Answer 1

Step-by-step explanation:

speed = distance / time

40 = 50 / T

T = 50 / 40

T = 5/4h

60 = 70 / T

T = 70 / 60 = 7/6h

total time taken = 5/4 + 7/6

30 + 28 / 24

58 / 24 = 29 / 12 hours

average speed = total distance travelled / total time taken

= 50 + 70 / 29 / 12

120 × 12 / 29

1440 / 29 km/h