Answer:
M = 175 kg
Explanation:
In the resolution of the harmonic oscillator movement of a system and a mass with a spring, the angular velocity is
w = √ k / m
Where k is the spring constant and m the mass
In this case the mass is the mass of the chair (m) plus the mass of the astronaut (M)
M all = m + M
The angular velocity and the period are related by
w = 2π / T
Substituting
2π / T = √(k/(m + M))
We calculate the astronaut's mass
4π² / T² = k / (m + M)
M = k T² / 4π² - m
M = 569 3.6² /(4π²) - 11
M = 186.8 - 11
M = 175 kg