There are 20+21= 41 people on the class. Let B be the grade points of the boys and G be the grade points of the girls. Since the class has a whole GPA of 2.96, we can write
[tex]\frac{B+G}{41}=2.96[/tex]On the other hand, the GPA of the boys is
[tex]\begin{gathered} \frac{B}{20}=2.40 \\ \text{then, the grade points of the boys is} \\ B=20\times2.40 \\ B=48 \end{gathered}[/tex]By substituting this result into the first equation, we have
[tex]\frac{48+G}{41}=2.96[/tex]After multiplying both sides by 41 and subtracting 48 in both sides, we get
[tex]\begin{gathered} 48+G=41\times2.96 \\ G=41\times2.96-48 \\ \text{then} \\ G=73.36 \end{gathered}[/tex]Since the GPA of the girls is
[tex]\frac{G}{21}[/tex]we get
[tex]\frac{73.36}{21}=3.49333[/tex]Hence, by rounding down to the nearest hundredth, the answer is 3.49