If the length of the pendulum string is 4 times its original length, what is the change in period?

Period is the reciprocal of frequency, so it would depend on how many times the pendulum swings in an interval of euclidean time. However, the square of the period varies directly with the length. By substituting 4L in for L in L= T(squared) where T equals root L, we get that T for 4L equals 2 root L. It would double the period.