A) \[5\text{ }min\]
B) \[60\text{ }min\]
C) \[20\text{ }min\]
D) \[30\text{ }min\]
Correct Answer: D
Solution :
Time taken by the boat to reach the other side is \[~Time=\frac{~~distance}{~relative\text{ }speed}\] Relative speed \[=\sqrt{{{5}^{2}}-{{3}^{2}}}=\sqrt{16}=4km/h\] \[\therefore \] \[T=\frac{1\,\,km}{4\,\,km/h}=0.25h\] To come hack boat takes the same time, hence total time is \[T'=2\times 0.25=0.5h\] Also, \[1\,h=60\min \] \[\therefore \] \[0.5\,h=30\,\min \]You need to login to perform this action.
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