Contingency table

[drist]

In a fictional class 40% of students are male, 60% of students are female. Of the male students 25% are less than 20 years old and 65% are between 20 and 30 years old. Of the female students 20% are less then 20 years old and half are between 20 and 30 uears old. make a contingency table to describe these variables.
I know that the 2 variables are female male and the ages and that the total for girls is .60 and boys is .40 but thats where I am lost. We didnt do any simular questions can any one help me? Please

 

[galactus]

One way to go about it is to assume a number of students. Say, 100 total. It's an easy number to deal with.

\(\displaystyle \begin{array}{c|c|c|c} \;\ & \text{male} & \text{female} & \text{total}\\ \hline \text{less than 20}& 10 &12 & 22 \\ \hline 20-30& 26 &30& 56\\ \hline \text{other}&4&18&22\\ \hline \text{total}&40&60&100\end{array}\)