Answer:
Step-by-step explanation:
velocity of a transverse wave is proportional to root of tension in the string
V α √ T
V = k √ T where k is a constant .

V₁ and V₂ are velocities of wave corresponding to tension of T₁ and T₂ in the string . Let T₁ be tension when the experiment was conducted on new planet and T₂ is tension when it was conducted on the Earth.
Tension will be equal to weight suspended so ,
where g is gravitational acceleration on new planet
V₂ = 4 / .039 = 102.564 m /s
V₁ = 4 / .0625 = 64 m /s

.389 =

g = 3.8 m /s²
g = G M / R² where G is universal gravitational constant , R is radius
3.8 = 6.67 x 10⁻¹¹ x M / (7.2 x 10⁷ ) ²
M = 29.53 x 10²⁵ kg .