A boy walks 800m in 20 minutes. Calculate his average speed in km per hour

  • A 2.4
  • B 4
  • C 16
  • D 24
waec 2004mathematics

The correct answer is A. 2.4

\(Average \hspace{1mm}speed = \frac{Distance}{Time\hspace{1mm} taken}\\

Distance = 800m = \frac{800}{1000}km = 0.8km\\

Time\hspace{1mm}taken = 20\hspace{1mm}minutes = \frac{20}{60}hr=\frac{1}{3}hr\\Average \hspace{1mm} speed = \left(0.8\div \frac{1}{3}\right)km/hr = (0.8\times3)km/hr\\=2.4km/hr\)

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