Answer:
1/20
Explanation:
The probability of any of the friends sitting on any of the seats is equal.
So the probability of Hamad sitting on the first seat = 1/5
As Hamad is sat on the first seat, there are now 4 available seats, so the probability of Riyadh sitting on the second seat = 1/4
Therefore, probability of Hamad sitting on the first seat AND Riyadh sitting on the second seat = 1/5 x 1/4 = 1/20