Answer: 2/21
Step-by-step explanation:
Number of white marbles = 2
Number of blue marbles = 5
Number of red marbles = 8
Total number of marbles = 15
The probability of picking the first blue marble will be 5/15 = 1/3
When the first marble is picked, there'll be 4 blue marbles and 14 total marbles left, then the probability of picking another blue marble will be 4/14 = 2/7.
Therefore, the probability of two blues in a row will be:
= 1/3 × 2/7
= 2/21