Three cars covered distances in the ratio 1 : 2: 3. If the ratio of the time of their travel is 3 : 2 : 1, then ratio of their speeds is :

$1: 3 : 9$

Distance = Speed × Time

                                  C1    :    C2    :      C3

Distance                       1     :      2    :        3

Time                             3     :     2    :         1

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Speed                \(\frac{1}{3}\) : \(\frac{2}{2}\) : \(\frac{3}{1}\)

                                    1    :     3     : 9

The correct answer is option (1) : $1: 3 : 9$