A) 4 kmph | B) 6 kmph |

C) 3 kmph | D) 2 kmph |

Explanation:

Let the speed of current = **'C'** km/hr

Given the speed of boat in still water = 6 kmph

Let **'d'** kms be the distance it covers.

According to the given data,

Boat takes thrice as much time in going the same distance against the current than going with the current

i.e, $\frac{\mathbf{d}}{\mathbf{8}\mathbf{}\mathbf{-}\mathbf{}\mathbf{C}}\mathbf{}\mathbf{=}\mathbf{}\mathbf{3}\mathbf{}\mathbf{\times}\mathbf{}\frac{\mathbf{d}}{\mathbf{8}\mathbf{}\mathbf{+}\mathbf{}\mathbf{C}}$

$\Rightarrow 24-3\mathrm{C}=8+\mathrm{C}\phantom{\rule{0ex}{0ex}}\Rightarrow 4\mathrm{C}=16\phantom{\rule{0ex}{0ex}}\mathbf{\Rightarrow}\mathbf{}\mathbf{C}\mathbf{}\mathbf{=}\mathbf{}\mathbf{4}\mathbf{}\mathbf{kmph}$

Hence, the speed of the current **C = 4 kmph.**

A) 2(2 + √17) | B) 3(2 + √17) |

C) 2(4 + √15) | D) 3(4 + √17) |

A) 0.20 Hz | B) 625 Hz |

C) 250 Hz | D) 100 Hz |