A clock loses exactly twenty minutes every hour. If the clock is set correctly at 12 noon, what is the correct time when the clock reads 4:00 pm?
Come back tomorrow for the correct answer to this teaser.
Answer for yesterday's Brain Teaser
For two equal natural numbers x and y, some operations are performed as:
Step 1: x = y
Step 2: x × x = y × x
Step 3: x2 – y2 = xy – y2
Step 4: (x + y) (x – y) = y (x – y)
Step 5: x + y = y
Step 6: y + y = y
Step 7: 2y = y
Step 8: 2 = 1
Obviously, this is incorrect. In which step was the mistake made?
Answer
In step 5, the previous equation was divided by (x – y). Since x = y, x – y = 0.
It is also known that one cannot divide by 0. This is where the problem lies.