Answer:
Answer is :

Explanation:
Total number of shirts : 12
- Blue shirts : 5 (fit blue shirts : 4 , too big blue shirts : 1)
- Green shirts : 7 (fit green shirts : 1, too big green shirts : 6)
We need to find the probability of randomly select a shirt which is blue or too big.
Here two conditions are blue or too big. Means we have to add the probability of both the conditions because of OR.
OR : one condition should satisfy at a time or the other one or both.(all conditions probability will add)
AND : all conditions should satisfy at a time.( all conditions probability will multiply)
- Probability of being a shirt blue =
=

- Probability of being a shirt too big =
=

∵ 6 = (7-1), because one too big shirt already counted in blue shirts probability.
∴ Probability of being a shirt blue or too big is :
+
=
