Gas X (molar mass M) has a speed of sound of 500m s−1 at a certain temperature. A mixture is prepared at the same temperature containing 2 mol of X and 3 mol of another gas Y whose molar mass is 4M. Both gases have the same ratio of specific heats. What is the approximate speed of sound in the mixture?
(a) 350m s−1
(b) 320m s−1
(c) 300m s−1
(d) 190m s−1