suppose that 3 digits are selected at random from the set S={1,2,3,4,5,6} and are arranged in random order. Find the probability that the resulting 3-digit number is less than 300.

Answer 1

Can digits be repeated?
I will assume they CANNOT

number of possible 3 digit numbers
= 6*5*4 = 120

to be less than 300, the number must start with either a 1 or a 2
number of such cases = 2*5*4 = 40

prob of event = 40/120 = 1/3