To find the time it takes for the crab to move a distance of 23 meters at a speed of 1.7 meters per second (ms), you can use the formula:
\[ \text{Time} = \frac{\text{Distance}}{\text{Speed}} \]
Plugging in the values:
\[ \text{Time} = \frac{23 , \text{m}}{1.7 , \text{m/s}} \approx 13.5 , \text{s} \]
So the answer is:
13.5 s