A cyclist rides 24 km at 16 kmph and further 36 km at 15 kmph. Find his average speed for the journey. · ABC26GN3666
Subject: General Aptitude · Chapter: Time and Distance · Exam: R.R.B. 2008
A cyclist rides 24 km at 16 kmph and further 36 km at 15 kmph. Find his average speed for the journey.
(a)15.38 kmph
(b)15.5 kmph
(c)16 kmph
(d)None of these
Answer
Explanation
Total distance travelled $=(24+36) \mathrm{km}=60 \mathrm{km}$. $$\begin{aligned} \text { Total time taken } & =\left(\frac{24}{16}+\frac{36}{15}\right) \mathrm{hr}=\left(\frac{3}{2}+\frac{12}{5}\right) \mathrm{hr}=\frac{39}{10} \mathrm{hrs} . \\ \therefore \text { Average speed } & =\left(60 \times \frac{10}{39}\right) \mathrm{km} / \mathrm{hr}=\left(\frac{200}{13}\right) \mathrm{km} / \mathrm{hr} \\ & =15.38 \mathrm{km} / \mathrm{hr} . \end{aligned}$$
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