Question posted by Jenny from Singapore:
Grade/Level: Primary 2
Question: A kitty is climbing up a tree which is 34m tall. In one minute, it will climb up 6m but slips down 2m. How long will the kitty take to reach the top of the tree?
Step 1: Since the kitty climbs up 6m and slips down 2m every minute, we can use arrows to illustrate this vertically. (I chose to use vertical models as it is has more visual impact than the horizontal ones for the kids since the question involves height.)
Step 2: The net effect is that it will climb up 6m-2m = 4m after the 1st per minute.
Step 3: Similarly, it will climb up 4m in the 2nd minute and so on.
Step 4: Hence, we can draw an arrow to show that this pattern repeats itself until the kitty reaches the full height of 34m.
Thus, from the model,
34m / 4m = 8.5 minutes or 8minutes 30seconds
However, this answers assumes that the climbing up and slipping down occurs simultaneously causing a consistent net increase in height of 4m per min.
If our assumption changes to the kitty only starting to slip after reaching every 6m, then the answer would be slightly different.
34m / 4m = 8min R 2m (8min with a remainder of 2m)
Therefore, it will take 8 min to climb the 1st 32m leaving 2m.
To climb 6m ------- 1 min
To climb 1m ------- 1/6 min
To climb 2m ------- 1/6 min x 2 = 1/3 min or 20 seconds
Hence, it will take 8 min 20 seconds to climb 34m.
As the question is unclear, this is the best explanation I can give.