Question

The chapter "Speed" has question no. 4 on page no. 12. Explain/Solve.

Answer 1

(a)

Total time taken	=	$\frac{4}{5}$ + 1$\frac{1}{5}$
	=	2 h

The total time taken for the whole journey was 2 hours.

(b)
3 units → 84 km

1 unit → $\frac{84}{3}$ = 28 km

5 units → 28 × 5 = 140 km

Total distance travelled = 140 km

Average speed	=	$\frac{\mathrm{Total}\mathrm{distance}}{\mathrm{Total}\mathrm{time}}$
	=	$\frac{140}{2}$
	=	70 km/h

The average speed for the whole journey was 70 km/h.