4. A class committee consists of 4 boys and 3 girls. Now, 2 people are to be selected to serve as the class president and vice president, with the probability that at least 1 girl is elected being $\qquad$ .


4. $\frac{5}{7}$ Consider the complementary event: no girls serve as the class president or vice president, there are $A_{4}^{2}$ ways to select, so, the probability is $1-\frac{A_{4}^{2}}{A_{7}^{2}}=\frac{5}{7}$.