"if all the possible n-digit numbers using n distinct digits are formed , the sum of all the numbers so formed is equal to (n-1)! * {sum of the n digits} * {1111...n times} "
Whats the formula if its a p-digit number using q-distinct digits ?
The first train to A leaves at 6:00 in the morning and there is a train to A after every 10 mins. First Train to B leaves at 6:06 in the morning and then there is train leaving for B every 10 minutes. Tom arrives to station any time between 10:00 AM to 11:00 AM every day and takes the first train that comes. what is the probaility that he will go to B on a given day? (assume there are only two trains one to A, other to B that come on Tom's platform)
3/5
If he arrives between 10:00 and 10:06 => He will take the train B ..