Question

a tortise moves at a distance of 100m in 15m .what is the average speed of tortoise in km/hr
if answer is0.4km/hr

Answer 1

speed = distance / time
          = 100/15
          = 6.6 m/s
          = 6.6 * (18/5)
          =23.76 km/hr

Answer 2

average speed = total distance/total time taken
on puting the numerical value we can get the answer ..
v = 100/900 =1/9 m/s on multiplying it by 18/5 to convert it ti km/hr 
1/9x18/5 =0.4km/hr