77. A school organizes 40 students from four classes of the first year junior high to visit the elderly at a nursing home. The students decide to make small cakes for the elderly themselves. It is known that in the same amount of time, 7 boys made 6 small cakes, and 3 girls made 4 small cakes. The number of students in each class is shown in the figure. Ask:
(1) Which class made the most cakes?
(2) How many cakes did the students from these four classes make together?
Answer: (1) Grade 7 (3); (2) 180.
Solution: (1) From the given conditions and the chart, we can get
\begin{tabular}{|c|c|c|c|c|}
\hline & Class 1 & Class 2 & Class 3 & Class 4 \\
\hline Girls & 24 & 18 & 27 & 21 \\
(Num) & 16 & 22 & 13 & 19 \\
\hline Boys & Num) & 16 & & \\
\hline
\end{tabular}

Since $\frac{4}{3}>\frac{6}{7}$, it is known that the work efficiency of female students is higher than that of male students. Given that the total number of students in each class is the same, the class with the most female students, Grade 7 (3), should have made the most cakes.
(2) The total number of students in these four classes is 160, among which the number of female students is $24+18+27+21=90$ (people), and the number of male students is
$$
40 \times 4-90=70 \text { (people). }
$$

The total number of cakes made by the students in these four classes is
$$
90 \times \frac{4}{3}+70 \times \frac{6}{7}=180 \text { (cakes). }
$$