1572. Let the germination rate of rye seeds be $90 \%$. What is the probability that out of 7 sown seeds, 5 will germinate?
Solution. The probability of germination of a single seed $p=$ $=0.9$. Therefore, $q=1-p=0.1$. By the Bernoulli formula, we determine

$$
P_{5,7}=C_{7}^{5} p^{5} q^{7-5}=C_{7}^{7-5} p^{5} q^{2}=C_{7}^{2} \cdot(0.9)^{5} \cdot(0.1)^{2}=0.124
$$