ABC26GN3669 · Time and Distance

Subject: General Aptitude · Chapter: Time and Distance · Exam: · Marks: · Difficulty:

A motorist covers a distance of 39 km in 45 minutes by moving at a speed of $x \mathrm{kmph}$ for the first 15 minutes, then moving at double the speed for the next 20 minutes and then again moving at his original speed for the rest of the journey. Then, $x$ is equal to :

(a)31.2

(b)36

(c)40

(d)52

Answer

Answer (as printed): B

Explanation

$$\begin{aligned} & x \times \frac{15}{60}+2 x \times \frac{20}{60}+x \times \frac{10}{60}=39 \\ & \Rightarrow \frac{x}{4}+\frac{2 x}{3}+\frac{x}{6}=39 \Rightarrow 3 x+8 x+2 x=468 \Rightarrow x=36 . \end{aligned}$$

Explanation as extracted from the printed page; notation may be imperfect.

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