A man covers half of his journey at 6 km/h and the remaining

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RRB ASM Exam (Ajmer) 2007 click here to view all questions

A man covers half of his journey at 6 km/h and the remaining half at 3 km/h. His average speed is

A9 km/h

B4.5 km/h

C4 km/h

D3 km/h

Nithin K ? Nov 20 '2016 at 21:47

Answer is : 4 km/h

Explanation:

Given,
A man covers half of his journey at 6 km/h = \(\frac{0.5j}{6} \).......(i)
the remaining half at 3 km/h = \(\frac{0.5j}{3}\) ................(ii)

Average speed = equation (i) + equation (ii)
\(\frac{j}{s}= \frac{0.5 j}{6} + \frac{0.5j}{3}\)
\(\frac{j}{s}=\frac{0.5j}{6} + \frac{j}{6}\)
\(\frac{j}{s} = \frac{1.5j}{6}\)
\(\frac{1}{s} = \frac{1.5}{6}\)
\(6 = 1.5 s\)
\(s = \frac{6}{1.5}\)
\(s = \frac{60}{15}\)
\(s = 4\)
---------------------------------------------------------------------------------------

Shortcut Formula: If Two speed is geven
\(\text{Average speed }= \frac{2xy}{x+y};\)
\(= \frac{2*6*3}{6+3};\)
\(= \frac{36}{9}\)
= 4 kmp/h.

All DiscussionsClick here to write answer

Answer is : 4 km/h Explanation: Given, A man covers half of his journey at 6 km/h = \(\frac{0.5j}{6} \).......(i) the remaining half at 3 km/h = \(\frac{0.5j}{3}\) ................(ii) Average speed = equation (i) + equation (ii) \(\frac{j}{s}= \frac{0.5 j}{6} + \frac{0.5j}{3}\) \(\frac{j}{s}=\frac{0.5j}{6} + \frac{j}{6}\) \(\frac{j}{s} = \frac{1.5j}{6}\) \(\frac{1}{s} = \frac{1.5}{6}\) \(6 = 1.5 s\) \(s = \frac{6}{1.5}\) \(s = \frac{60}{15}\) \(s = 4\) --------------------------------------------------------------------------------------- Shortcut Formula: If Two speed is geven \(\text{Average speed }= \frac{2xy}{x+y};\) \(= \frac{2*6*3}{6+3};\) \(= \frac{36}{9}\) = 4 kmp/h. Nithin K ? answered Nov 20 '2016 at 21:47 All Comments

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