Answer:
k = 77/10
Explanation:
The jar consist of blue, red and green marbles . The probability of each of them can be described as follows.
probability of blue marbles = 2/7
probability of red marbles = 3/k
probability of green marbles = 5/2k
The sum of the individual probability is equals to 1. Therefore,
2/7 + 3/k + 5/2k = 1
collect like terms
(6 + 5)/2k = 1 - 2/7
11/2k =(7 - 2) /7
11/2k = 5/7
cross multiply
10k = 77
divide both sides by 10
k = 77/10