P(Larger or blue) = 7/10. In a bag we have blue and red marbels, which are large and small as in the table shown in the image, the probability of taking a large or blue marble is 7/10.
The key to solve this problem is find the probability of the union events using the equation P(A∪B) = P(A) + P(B) - P(A∩B).
For this problem we have P(Large or Blue) = P(Large) + P(Blue) - P(Large and Blue). The total of the large ones is 25 and the small ones is 15, meaning that the sum of both is 40. P(large) = 25/40, P(Blue) 20/40, and P(Large and Blue) = 17/40
P(Large or Blue) = 25/40 + 20/40 - 17/40 = 28/40 dividing by 4 both terms of the fraction.
P(large or Blue) = 7/10