[數學]機會率問題

1. 現在有60部電腦，其中10部壞的。
現在購買兩部如果買的電腦有損壞 可以退回
[可以退回全部 假如二部都是壞的 只可以退一次]
問到最後兩部都是沒有壞的機會率是？


2. On a production line, an inspector is starting to check the quality of the products.
The inspector selects products at random and classifies them into three classes: Class A (Good), Class B (Bad)
and Class C (Very Bad). From the past statistics, it is known that 90% of the products fall into Class A, 9% fall into
Class B and 1% fall into Class C. The inspector will shut down the production line

if:
i. A Class C product is inspected;
ii. Two Class B products are inspected consecutively.

Find
the following probabilities:
(1) The production line is shut down after the first inspection;
(2) The production line is shut down after the second inspection.