2. In a class with 15 boys and 6 girls, we select one pair. What is the probability that the pair will include at least one girl?
2. Let's calculate the probability that both in a pair will be boys.

The total number of pairs we can make from 21 students is $\frac{21 \cdot 20}{2}=210$.

1 POINT

From 15 boys, we can make $\frac{15 \cdot 14}{2}=105$ pairs.

1 POINT

The probability that both in a pair will be boys is $\frac{105}{210}=\frac{1}{2}=0.5=50\%$.

2 POINTS

The probability that at least one girl is in the pair is $1-\frac{1}{2}=\frac{1}{2}=0.5=50\%$.

2 POINTS

TOTAL 6 POINTS