Solve this please

Ice Hot Item Water Soda Cream Dog $ $3 $3 $5 $4 Proportions sold 0.2 0.25 0.35 0.2 At a California beach, a vendor sells just four items out of a small cart. Water, Soda, Ice Cream, Hot dog. The cost of each item is shown on the table along with the proportions of all the items sold in the long run. What is the standard deviation representing the variability in amount made in the long run? If the answer is a non-terminating decimal or terminating decimal that is longer than three decimal places, round to three decimal places. Otherwise, write down the exact decimal value. A