12 October 2005

Answer to PSLE Math Question

Looks like everyone is curious about the correct answer to the following question:

A man went down a flight of stairs by walking a few steps and running 14 steps, taking a total of 41s. He repeated this by walking a few steps and running 6 steps, taking 65s to do so. What would be time taken if he only walked down the flight of stairs?

to be honest, I was inititally stumped by the question as well. But i still manage to figure it out anyways. :p Looks like my A* grade for my PSLE MAth was deserving!

The trick is: think simple, guys!

Walk few steps + run 14 steps = 41 seconds

Walk few steps + run 6 steps = 65 seconds

Therefore, a 8 step difference results in a difference of 65 - 41 seconds = 24 seconds

8 steps = 24 seconds

1 step = 3 seconds,

which means, for every step you walk, you will take 3 extra seconds than that if you run.

Hence, if the boy WALKS DOWN THE WHOLE FLIGHT OF STEPS:

65 seconds + (6 X 3 seconds)
= 65 + 18
= 83 seconds

CHECK ANSWER:

1 step = 3 seconds
14 steps = 41 seconds
13 steps = 44 seconds
12 steps = 47 seconds
11 steps = 50 seconds
10 steps = 53s
9 steps = 56s
8 steps = 59s
7 steps = 62s
6 steps = 65s
5 steps = 68s
4 steps = 71s
3 steps = 74s
2 steps = 77s
1 step = 80s
0 steps / Walk down the whole thing = 83s

You DO NOT need to know the total number of steps to do this question! :)

Q.E.D

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