Underwater acoustic communication. Refer to the IEEE Journal of Oceanic Engineering (Apr. 2013) study of the characteristics of subcarriers—telecommunication signals carried on top of another—for underwater acoustic communications, Exercise 4.80

(p. 241). Recall that a subcarrier can be classified as either a data subcarrier (used for data transmissions), a pilot subcarrier (used for channel estimation and synchronization), or a null subcarrier (used for direct current and guard banks transmitting no signal). In a sample of 1,024 subcarrier signals transmitted off the coast of Martha’s Vineyard, 672 were determined to be data subcarriers, 256 pilot subcarriers, and 96 null subcarriers. Suppose a communications engineer who works near Martha’s Vineyard believes that fewer than 70% of all subcarrier signals transmitted in the area are data subcarriers. Is there evidence to support this belief? Test using a = .05.