Answer: 111.11 seconds
Explanation:
Given: The period of a pendulum is the time the pendulum takes to swing back and forth
The function relates the length
in feet of a pendulum to the time t in seconds that it takes to swing back and forth.
If L= 90 feet then put this in the above function, we get
![90=0.81t\\\\\Rightarrow\ t=(90)/(0.81)\\\\\Rightarrow\ t=111.1111111\approx111.11\text{ seconds}](https://img.qammunity.org/2021/formulas/mathematics/high-school/rul803szvcl6mlewkprns4pquzf6moil9t.png)
Hence, the period = 111.11 seconds