Random Variables- Properties of Variance/Standard Deviation

A mason is contracted to build a patio retaining wall. Plans call for the base of the wall to be a row of 50 10-inch bricks, each separated by ½ inch thick mortar.  Suppose that the bricks used are randomly chosen from a population of bricks whose mean length is 10 inches and whose standard deviation is 1/32 inch.  Also suppose that the mason, on the average, will make the mortar ½ inch thick, but the actual dimension varies from brick to brick, the standard deviation of the thickness being 1/16 inch.  What is the standard deviation of L, the length of the first row of the wall?