Answer:
Frequency, f = 0.38 Hz
Step-by-step explanation:
Time period of the spring, T = 2.6 seconds
We need to find the frequency of oscillation for a mass on the end of spring. The relation between the time period and the frequency is given by :
Let f is the frequency of oscillation. So,

f = 0.38 Hz
or
f = 0.4 Hz
So, the frequency of oscillation for a mass on the end of a spring is 0.38 hertz. Hence, this is the required solution.