You can use proportional reasoning to answer this question.
Set up a ratio with how far she traveled in the first 2 1/3 mins. Make is equal to x feet in 8 minutes. Solve using cross products.
1r feet x feet
2 1/3 min = 8 mins
8r feet = 2 1/3 x
2 1/3 2 1/3
3 3/7r feet = x
In 8 minutes, Maggie descended 3 3/7r feet.