Question

A man was trying to swim to a buoy placed at a distance of 200 m out in a sea. it took him 1 min to swim 20 m . then a wave pushed him 10 m back and he rested for about 1 min brofre swimming again. he continued in this way for the rest of the journey . how long would it take the man to sim to the buoy..

Answer 1

How many minutes does it take him to make a net of 10m of progress?

Answer 2

Or another way to think of it is:

After 1 minute he is ___ m closer to the buoy
After 2 minutes he is ___ m closer to the buoy
After 3 minutes he is ___ m closer to the buoy
After 4 minutes he is ___ m closer to the buoy

Think about the pattern of how he is progressing toward the buoy.

Answer 3

according to the answer key answer is 37

Answer 4

I think the last minute is not counted!?
It should be 39 then?

Answer 5

Ah, I get it.

After 36 minutes, he's gone how far?

In the next minute, he goes how far?

Answer 6

@ali_imam, I got your message, here's what I'm saying:

In one minute he goes 20 m, then gets pushed back 10, then rests for 1 minute. So after the first 2 minutes he has made 10 m of progress toward the buoy.

In the 3rd minute he goes 20 m, then gets pushed back 10, then rests for 1 minute. So after the first 4 minutes he has made 20 m of progress toward the buoy.

This pattern continues, where he is making 10 m of progress every 2 minutes. So after 36 minutes, how far has he gone?

\(\large \dfrac{10m}{2min} \cdot 36min = 180m\)

Right? Now after his rest is over, in minute 37 he goes 20 more meters. Where does that put him, at the end of minute 37 (and immediately before the wave pushes him back)?

Answer 7

Excellent answer mate! :)

Answer 8

Thanks, @AkashdeepDeb :)