Answer:
1/6 of the students in Joel's grade have both a sister and a brother
Step-by-step explanation:
We have that:
1/5 of the students have a sister.
Of those who have a sister(1/5), 5/6 also have a brother. So
[tex]\frac{1}{5}\ast\frac{5}{6}=\frac{1}{6}[/tex]1/6 of the students in Joel's grade have both a sister and a brother
