Not sure how to answer - Habs Boys Maths 2014

[Stokers]

Hello, DD completed this paper yesterday and DH and she disagree about the answer to the following:

Question 2
In the winter, I try and climb up an icy slope starting at the bottom. Each time I
make a move I find that I go up four metres but then slide back down two metres.
How many moves do I need to get to the top which is 8 metres up the slope from
the bottom?
___________

DH says that because you would have reached the top at move 3, even though you would then slip back 2 metres. DD says 4 moves to actually reach and stay at the top. Who is right? Suggestions,please!
Thanks.
Stokers

[Guest55]

In the winter, I try and climb up an icy slope starting at the bottom. Each time I
make a move I find that I go up four metres but then slide back down two metres.
How many moves do I need to get to the top which is 8 metres up the slope from
the bottom?

I think the answer is three because once you are at the top you can move on.

First move: up 4 to 4 metres from top but slip back 2 - so now 6 metres from the top

Second move: up 4 to 2 metres from the top but then slip back 2 - so now 4 metres from the top

Third move: up 4 metres so at the top.

There are other problems like this - frog in a well etc.

[nyr]

DD thought it was 3 moves - her reasoning being that as soon as you reach the top the ground is not sloped and you won't slide back down. I thought it was 4 moves, as you wouldn't move 4m up and 2m down in discrete movements but continually a bit up and a bit down. I accepted DD's reasoning but clearly there's some ambiguity in the question. Should one apply common sense or follow the exact wording?

nyr

[Stokers]

Thanks, Guest55 and nyr - I'm in the 3 moves camp, I think, as you will reach the top in 3 moves, even if you do then slide down again!