At a certain bakery, the price of each doughnut is $1. 50. Let the random variable d represent the number of doughnuts a typical customer purchases each day. The expected value and variance of the probability distribution of d are 2. 6 doughnuts and 3. 6 (doughnuts)2 , respectively. Let the random variable p represent the price of the doughnuts that a typical customer purchases each day. Which of the following is the standard deviation, in dollars, of the probability distribution of p ?.