A pendulum with a length of precisely 1000 m can be used to

Question

Solve the all parts of following problem given below:

Problem: A pendulum with a length of precisely 1.000 m can be used to measure the acceleration due to gravity g. Such a device is called a gravimeter.

Part A: How long do 183 oscillations take at sea level, where g = 9.81 m/s²?

s

Part B: Suppose you take a gravimeter to the top of a high mountain, where the value of g is 0.29% less than the value at sea level. How long do 183 oscillations take at the top of Mount Everest?

s

I am having a hard time understanding these questions. So if you answer please explain how you found the answers.