A 90 kg skydiver hanging from a parachute bounces up and down with a period of 1.5 seconds. What is the new period of oscillation when a second skydiver, whose mass is 60 kg, hangs from the legs of the first?

I am using the equation T = 2pie square root of m/k.

I found k and then combined the 2 masses (m1+m2), and put that back into the equation and found an answer but not the right one.

The right answer is suppose to be 1.94 s ....i'm getting 58