I'm confused on part C on weather rot not to use that equation for stand deviation?

(P ( X735 )70.06\\7) 2. According to a CNN report, 6% of the population do not have traditional phones and instead rely on only cell phone. A random sample of 720 telephone users is obtained. Given = = 0.06, 1-720-94 n=720 a) Describe the sampling distribution of p-hat, the sample proportion that are "cell phone only" np z zio # n( i- p ) 7= 10 n . P = 720 . ( . 06) = 43.2 720. (1- 0. 06)= 676.8-# $ M P = P = 0 . 06 + 8 = VP (1-P) = V0. 06 (1- 0. 06): 720 = (0. 000850) b) In a random sample of 720 telephone users, what is the probability that more than 8% are "cell phone only"? X - N ( M = 0 . 0 6 , 5 = 0. 008850) + P (X70.08) = 1-P (X>0.08) 2 = (x - M ) : 0 = 2 = (0. 00 - 0. 06) 10. 00 0850= 7=2.26 P ( x 7 0 0 08 ) = 1 - P ( 2 ( 2 . 2 6 ) = P ( x > 0 . 08) = 1-. 98081 + (P ( X 70.00)= 0.0119 ) c) would it be unusual if a random sample of 720 adults results in 80 or fewer being "cell phone only" J = V N . P . CI- P )