prob of colliding is= 1st and 2nd moving towards each other + 2nd and 3rd moving towards each other + 3rd and 1st moving towards each other= (1/2)* (1/2) + (1/2)* (1/2) + (1/2)* (1/2) = 3/4
probability of not colliding = 1- 3/4 = 1/4
For continuous clock where hours and minutes hands move continuously then the answer is 7.5 Minutes. 3.25* 30 - 15*6 = 7.5
For discrete clock where minutes hand moves after 60 secs and hours hand moves after 12 mins then the answer is 6 minutes.