clock puzzle

At how many minutes past 8 O' clock does the minute arm and the hour arm coincide between 8 O' clock and 9 O' clock?



Answer:

If the two arms meet after y min
then the hour arm has moved by (30/60) y

the minute arm has moved by (360/60)y

now, (360/60)y = 240 + (30/60)y  ........... note this step

therefore, y = 43 (7/11)  mins

So, the two arms of the clock will coincide at 8: 43 (7/11)