1. The mirror clock problem
Joey leaves his house in the morning to go to day camp. Just as he is leaving his house he looks at an analog clock reflected in the mirror.
There are no numbers on the clock, so Joey makes an error in reading the time since it is a mirror image. Joey assumes there is something wrong with the clock and rides his bike to day camp.
He gets there in 20 minutes and finds that just as he gets there the day camp clock has a time that is 2 1/2 hours (2 hours and 30 minutes) later than the time that he saw in the mirror image of his clock at home.
What time was it when he got to day camp?
(The clock at camp and the clock at home were both set to the correct time.)
Ans: First subtract 20 minutes from 2 1/2 hours to compensate for his 20 minute bike ride to give a difference of 2 hours and 10 minutes.
To be a "Mirror Effect" it must be mirrored around 12 o'clock (when the hands are straight up), or around 6 o'clock (when the hands are pointing up and down), as we know he left in the morning, it must be 6 o'clock.
So, divide that 2 hours and 10 minutes by 2 and this will give you the center-point (65 minutes) for compensating for the mirror.
By adding that 65 minutes to 6 o'clock you get the time he left home (7:05), and the time he saw in the mirror (4:55).
Furthermore, by re-adding the 20 minutes from when he left (7:05), you get what time he got to camp (7:25).

2. The burning fuse problem
In front of you are several long fuses. You know they burn for exactly one hour after you light them at one end.
But the entire fuse does not burn at a constant speed. For example, it might take five minutes to burn through half the fuse and fifty-five minutes to burn the other half.
With your matchbox and using these fuses, how can you measure exactly three-quarters of an hour of time?
Ans: Light both ends of one fuse. At the same time light one end of a second fuse. The first fuse will finish in half an hour.
At that point the second fuse will be half done (in time, not necessarily in distance) and you immediately light its other end. The second half hour will now take only quarter of an hour.
Total time: half an hour plus quarter of an hour equals three-quarters of an hour.

3. Trick dog puzzle
A girl, a boy, and a dog are walking down a road together. The boy walks at 5 km/h, and is just behind the girl who walks at 6 km/h. The dog runs from boy to girl and back again with a constant speed of 10 km/h. The dog does not slow down on the turn.
How far does the dog travel in 1 hour?
Ans: This is a trick question, as we already hinted. The dog runs 10km, because its speed is 10 km/h and it doesn't slow down at all.
Where the boy and girl are has no effect on answering this puzzle. But if you asked WHERE the dog is after 1 hour ... that would be a very hard question to answer!
Courtesy: mathsisfun.com