From P to M, speed = 30mph
From M to N, speed = 50mph
From N to Q, speed = 60mph
Question=> What is the average speed of the bus throughout the whole journey?
Let distance P to M = x, M to N = y and N to Q =z.
$$Average\ speed\ of\ the\ whole\ journey\ =\frac{\left(x+y+z\right)}{\left(\frac{x}{30}+\frac{y}{50}+\frac{z}{60}\right)}$$

In statement 1: The ratio of time the bus took to cover the distance PM, MN and NQ is respectively 2 : 1 : 3.
Let the time taken for individual parts be 't'. Hence, time will be in ratio 2t : 1t : 3t.
Distances are x, y and z respectively. Therefore,
$$\frac{x}{30}=2t;\ \ \ \ \ \ x=60t$$
$$\frac{y}{50}=t;\ \ \ \ \ \ y=50t$$
$$\frac{z}{60}=3t;\ \ \ \ \ \ z=180t$$
$$Average\ speed=\frac{\left(total\ dist.\ travelled\right)}{total\ time\ taken}=\frac{\left(x+y+z\right)}{\left(\frac{x}{30}+\frac{y}{50}+\frac{z}{60}\right)}$$ $$=\frac{\left(60t+50t+180t\right)}{\left(\frac{60t}{30}+\frac{50t}{50}+\frac{180t}{60}\right)}=\frac{290t}{6t}$$
$$=\frac{145}{3}=48.33mph$$
$$Hence,\ statement\ 1\ is\ SUFFICIENT$$

For statement 2: Out of the 3 distances, WQ is 3 times the distance PM and more than 3 times the distance MN. The information provided here does not give us the exact distance of MN. Thereby, makes 'y' an unknown variable.
Hence, statement 2 is INSUFFICIENT

Option A is the correct answer because statement 1 alone is sufficient