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Rates, SM-Bank 045 MC

Barry lives 30 kilometres from the library.

On Tuesday, he drove to the library and averaged 90 kilometres per hour.

On Thursday, he took the train which averaged 30 kilometres per hour.

What was the extra time of the train journey, in minutes, compared to when he drove on Tuesday?

  1. \(20\)
  2. \(30\)
  3. \(40\)
  4. \(60\)
Show Answers Only

\(C\)

Show Worked Solution
\(\text{Time Driving}\) \(=\dfrac{\text{Distance}}{\text{Speed}}\)
  \(= \dfrac{30}{90}\)
  \(= \dfrac{1}{3}\ \text{hour}\)
  \(=20\ \text{minutes}\)

 

\(\text{Train Time}\) \(=\dfrac{30}{30}\)
  \(= 1\ \text{hour}\)
  \(= 60\ \text{minutes}\)

 

\(\therefore\ \text{The extra time taking the train}\)

\(=60-20\)

\(= 40\ \text{minutes}\)

 
\(\Rightarrow C\)