1. A box of fuses contains 20 fuses, of which five are defective. If three of the fuses are selected at random and removed from the box in succession without replacement , what is the probablility that all three fuses are defective?
2. If we twice flip a coin, what is the probability of getting at least one head?
3. In the past three years you made 6%, 9% and 5%. What is the standard deviation of your returns?
2.80%
2.08%
2.12%
2.00%
1.89%