# Clocks - Time

• Jun 9th 2008, 11:55 AM
MathLearner
Clocks - Time
Clock A,B and Cstrikes every hour. B slows down and take 2 minutes longer than A per hour while C becomes faster and takes a minute less than A per hour. If they strike together at 12 midnight, when will they strike together again...?

ans: 11 am
• Jun 10th 2008, 12:16 PM
Soroban
Hello, MathLearner!

Quote:

Clocks $\displaystyle A, B\text{ and }C$ strike every hour.
$\displaystyle B$ slows down and take 2 minutes longer than $\displaystyle A$ per hour
while $\displaystyle C$ becomes faster and takes a minute less than $\displaystyle A$ per hour.
If they strike together at 12 midnight, when will they strike together again?

Answer: 11 am . . . . I don't agree!

Clock A strikes every 60 minutes.
Clock B strikes every 62 minutes.
Clock C strikes every 59 minutes.

The LCM of 60, 62, and 59 is: .109,740

$\displaystyle 109,\!740\text{ minutes} \:=\:1829\text{ hours} \:=\:76\text{ days, }{\color{blue}5\text{ hours}}$

$\displaystyle \text{They will strike together at }{\color{red}5\text{ am}}\text{ (of the 77th day).}$

• Jun 11th 2008, 12:55 AM
MathLearner
I am not sure about this... In the paper i was solving, the right option given was for 11 am.. there was no option as 5 am...