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April 9, 2009

Clock Puzzles



If a clock takes 7seconds to strike 7, how long will the same
clock take to strike 10?

6 comments:

philofsci said...

3 seconds.

so it takes 1 second for every "hour"
7 seconds to get from 12 to 7. and since it's already on 7 ("the same clock") it only has 3 to go to get to 10.

Secret Squïrrel said...

I think the question is asking how long it will take a clock to chime 10 times to indicate that it is 10 o'clock.

If it takes seven seconds to strike 7 and we start timing at the beginning of the first strike, then the gap between each strike is 7 / 6 seconds.

There will be 9 intervals when striking 10 so it will take (10 * 7) / 6 = 11 2/3 seconds.

Anonymous said...

No it will be 9*7/6 seconds.

Secret Squïrrel said...

Gah! I am a numbnut. I said 9 intervals and then plugged 10 into the equation. (Works out to 10.5 s)

Note to self: always check your work before handing it in

Anonymous said...

363 seconds til the clock has struck 10
or is that 56 seconds
or maybe 115 seconds

Bitter Reality said...

Ans: 17 seconds
Explanation:
Lets think about the second hand.
If it takes 7 seconds to reach 7 then initially it was at 2 ticks(2 seconds before 6).So from 7 it will take 15 ticks(i.e.7 seconds) to reach at 10 while from the initial point it will take 10+7 = 17 seconds to reach 10.