Doubt in probability question, random distribution

[user3370]

i got that every number in the range must have same probability

for the first case, prob of a single variable will be 1/105 and for the second case will be 1/210

but beyond that i didn’t get anything from explaination, please help me

[Joan]

In the first case, since a <= 3, all the numbers from 3 to 7 inclusive are within the range a-b. That might not be the case for P(0 <= X <= 5) = 1/35. So, it will not be 1/210. Try reading the explanation again.

[user3370]

oh man, excluding 0-2 from the range was the tricky part. i wasn’t not getting the part why did we had two probabilities

tried to understand the question and solution from the start again

got it thanks