Answer: 17.5 kN
Explanation:
force downward on student: 
mg+142-mv^2/r=0

mg=mv^2/r-142

mv^2/r=mg+142 

at bottom, apparent weight
weight=mg+mv^2/r=mg+mg+142

apparent weight= 89(2g)+142



for force at bottom, reverse v^2/r

force=m(g+v^2/r) = 89 ( 9.8 + v^2 / 19 )
F = mg + mv^2 / r
F = mg + mg + 142 = 2mg + 142 = 2 x 89 x 9.8 + 142 = 17.5 kN