Question 9

1. Read data points from the line graph:
   The graph plots $R = \frac{\text{Male}}{\text{Female}}$:

   • For 2011: $R_{2011} = \frac{M_{2011}}{F_{2011}} = 1.0 \implies M_{2011} = 1.0 \times F_{2011}$.
   • For 2012: $R_{2012} = \frac{M_{2012}}{F_{2012}} = 1.5 \implies M_{2012} = 1.5 \times F_{2012}$.

2. Apply the given condition:
   The number of female students in 2011 and 2012 is equal: $F_{2011} = F_{2012} = F$.

3. Calculate the ratio:

   $$\frac{M_{2012}}{M_{2011}} = \frac{1.5 \times F}{1.0 \times F} = 1.5 = 1.5 : 1.$$

This corresponds to option C.