Сыни ойлау22 мин

Probabilities

P, AND, OR, NOT, conditional — the tools that cover almost every NUET probability item.

Core formulas

P(A) = \dfrac{\text{favourable}}{\text{total}}

P(\overline{A}) = 1 - P(A)

P(A \text{ and } B) = P(A) \cdot P(B)\quad (\text{independent})

P(A \text{ or } B) = P(A) + P(B) - P(A \text{ and } B)

P(A \mid B) = \dfrac{P(A \text{ and } B)}{P(B)}

‘At least one’ problems are almost always easier via the complement: $1 - P(\text{none})$ .

At least one head

Toss 3 fair coins. Probability of at least one head?

Жауап: $7/8$

Жаттығу

A class is 60% female. Of females, 50% study CS. What % of the class is female AND studies CS?

Жауап пен түсініктемені көру

Жауап: 30%

$0.6 \cdot 0.5 = 0.3$ .