Answer:
Step-by-step explanation:
As per given , The jar contains
Red marbles = (R1) , (R2) , (R3) , (R4)
Blue marbles = (B1) , (B2) , (B3) , (B4) , (B5) , (B6) , (B7) , (B8) , (B9) , (B10) .
Total marbles = 4+10=14
The marbles that has even number = (R2) , (R4) ,(B2) , (B4) , (B6) , (B8) , (B10)
=7
Total Blue marbles = 10
Blue and even marbles = 5
Now , the number of marbles are blue or even numbered :
n(Blue or even )= n(Blue) + n(even)- n(Blue and even)
= 10+7-5 =12
Now , the probability the marble is blue or even numbered will be :

Hence, required probability =