Answer
$T = 170~N$
Work Step by Step
We can use the equation for centripetal force to find the tension in the rope at the lowest point;
$\sum F = \frac{mv^2}{r}$
$T-mg = \frac{mv^2}{r}$
$T = \frac{mv^2}{r} + mg$
$T = \frac{(10.2~kg)(5.5~m/s)^2}{4.5~m} + 100~N$
$T = 170~N$
