Refer to the equation you derived in exercise (4). Assume that

1 y = 0.30m and 2 y = 0.10 m. What is the initial total mechanical
energy if the pendulum is released from rest? What is the speed of
the pendulum bob at the lowest point if the total mechanical
energy is conserved?

Is there some way we are supposed to know what exercise 4 is? My crystal ball is on the blink.