There are 20 poles with a constant distance between each pole. A car takes 22 seconds to reach the 12th pole starting from the first pole, with a constant speed between each pole. how many seconds will it take to reach the last pole?
Is the answer 36 seconds?
since $\frac{22} {12} = 1.83 $
$1.83 \times 20 = 36.67 $
Best Answer
Count the green distances between the poles. Notice: There are !!!$19$!!! of them. Not $20$. This is because you are starting at point $1$. The car never traveled between $0$ to $1$.
It started at $1$. And notice to get to post number $12$ (in red), the car only drove !!$11$!!! of the green distances.
So it took $22$ seconds to go $11$ distances. That is it took $\frac {22}{11} = 2$ seconds to go $1$ distance.
It will take $19*2 = 38$ seconds to go $19$ distances and to end up at post number $20$.
....
Also notice. If we relabeled the posts so that the first post is label $0$ and the second post is labelled $1$ and so on... well, how does that change the math. Nothing has changed but the label. Which labelling system makes more sense if you are starting at the first post and measuring the distances you travel?