see, what is equilibrium constant; it is the ratio of amt of products to reactants, you know that Kp does not change; and the question asks about the equilibrium yield so at equilibrium the Kp is unchanged so higher pressure will NOT affect the amt of methanol AT EQUILIBRIUM.As far as i know a change in pressure does affect the equilibrium position when there are gases involved.....an increase in pressure favors the side with fewer moles, so in the case of methanol i think the products side was favored.....it is only the equilibrium CONSTANT that is not affected by a change in pressure...