Solution:
Since the sample size is fixed;
[tex]n=7[/tex]And the probability of picking a girl is constant for each trial, the binomial distribution is appropriate;
[tex]\begin{gathered} P(X=r)=^nC_rP^r(1-P)^{n-r} \\ \\ P(X\leq2) \end{gathered}[/tex]Thus;
[tex]\Rightarrow^7C_0(0.45)^0(0.55)^7+^7C_1(0.45)^1(0.55)^6+^7C_2(0.45)^2(0.55)^5[/tex][tex]\Rightarrow0.0152+0.0872+0.2140=0.3164[/tex]ANSWER: 0.32
