12 bottles are on a shelf 8 bottles are cola 4 of them are d

12 bottles are on a shelf. 8 bottles are cola. 4 of them are diet cola. If 2 bottles are selected randomly, find the probability that they are both diet cola

Solution

Number of diet cola bottles = 4

Total number of bottles = 12

Probability that if 1st bottle selected is diet cola = 4/12 = 1/3

Probability that 2nd bottle selected is also diet cola = 3/11

Overall probability that 1st and 2nd bottles are both diet cola = (4/12) * (3/11) = (1/3) * (3/11) = 1/11

Answer is 1/11