Step 2 We are tasked to find the number of calls, n, Lori made to obtain o- = 0.05 for p = 0.20. Recall the formula to calculate the standard error for a proportion, p, for a given sample of size n. p(1 - p) n Solve the above formula for n, the number of calls. On = p(1 - p) On= p(1 - p) On= _2 p(1 - p) On= p(1 - p) _2 P On= p(1 - p) 5 - 2 X