The Brandywine River is at its flood stage of 9 ft. It’s continuing to rain. The next measurement shows that the river has risen 1 1/2 ft. ft. An additional measurement shows that the river has risen 1 5/12 ft. ft. How many more feet does the river need to rise to be at the major flood stage of 13 ft.? Express your answer in simplest form.
The total rise of the river is 1 1/2 + 1 5/12 = <<1+5/6=13/2>>13/2 = <<13/2=6.5>>6.5 ft
The river still needs to rise 13 - 6.5 = <<13-6.5=6.5>>6.5 ft. Answer: \boxed{6.5}.