Andy and jim are going to compete in the 100-meter dash against each other. let a be the time it takes andy to complete the race, and j be the time it takes jim to complete the race. based on previous results, they know that mu_a=11.5μ a =11.5mu, start subscript, a, end subscript, equals, 11, point, 5 seconds and \sigma_a=1σ a =1sigma, start subscript, a, end subscript, equals, 1 second. they also know that \mu_j=10.5μ j =10.5mu, start subscript, j, end subscript, equals, 10, point, 5 seconds and \sigma_j=0.5σ j =0.5sigma, start subscript, j, end subscript, equals, 0, point, 5 seconds. assume that their times are independent. let ddd be the difference between their times in a random 100-meter dash (d=a-j)(d=a−j)left parenthesis, d, equals, a, minus, j, right parenthesis. find the standard deviation of ddd.