Predict before reading A-E

A short prediction protects you from attractive wording.

After identifying the model, say the answer in plain language: “demand shifts right,” “the fourth worker should be hired,” or “the market produces too much because an external cost is ignored.” Your prediction need not contain the final vocabulary. It only needs direction and mechanism. Then compare each option with it.

Prediction changes the task from choosing among five polished statements to testing five claims against one economic rule. Without a prediction, the first familiar phrase can anchor your attention. With a prediction, an option must earn its place by matching the variable, direction, and mechanism you already identified. This is especially useful when all five choices contain legitimate vocabulary.

Make the prediction conditional when the evidence is conditional. With simultaneous increases in demand and supply, quantity certainly rises while price is ambiguous unless the relative shifts are known. A premature prediction that price rises would manufacture information the stem did not supply. Good prediction is disciplined, not overconfident: state what the model determines and preserve uncertainty where it does not.

Strong distractors are not nonsense. They often use the wrong curve, reverse causation, confuse a total with a marginal value, or omit a necessary step. An option can be partly true but incomplete. If positive profit attracts entry, “more firms enter” is true. If the question asks about price, the better answer continues the chain: entry raises market supply and lowers price.

Five recurring distractor families deserve deliberate checks. A neighboring concept uses a related rule, such as average cost when marginal cost is required. A reversed mechanism predicts that a price ceiling creates a surplus instead of a shortage. A wrong horizon gives a valid long-run entry result for a short-run firm. A wrong level substitutes the market quantity for one firm’s output. An incomplete chain begins correctly but stops before the variable asked about changes. These options are plausible because each borrows part of the right analysis.

Predict, then diagnose

The wage is $90 per day. Successive workers add $130, $110, $85, and $60 to daily revenue. Before reading the options, predict: hire the first two workers and stop before the third because the third adds less revenue than cost. “Hire three because total revenue still rises” confuses a positive marginal contribution with a profitable contribution. “Hire one because the second worker is less productive” confuses diminishing marginal returns with the point at which hiring should stop.

The words all, always, and never deserve scrutiny but are not automatically false. In the basic competitive model, a binding price ceiling below equilibrium always creates excess demand. Judge the assumptions rather than using grammar as a guessing trick.

Likewise, do not choose the longest option because it sounds qualified or reject the shortest because it seems too simple. Exam writers may use a concise equality such as P=MC as the complete efficiency condition in the stated model. Read every word for economic scope. “A monopoly charges the highest possible price” is wrong because the firm chooses a price-output combination that maximizes profit, not the largest price on demand. Adding technical vocabulary cannot repair the mechanism.

When two choices remain, state why each would be true. If one requires an unstated assumption, it is weaker. For example, a demand increase raises both equilibrium price and quantity when supply slopes upward. A claim that seller revenue must rise is also true in that simple case, but a claim that seller profit must rise requires cost information and a time horizon. The option with the complete supported chain wins over the one that reaches beyond the evidence.

Use units as a second answer key

Marginal cost is dollars per additional unit, profit is total dollars, elasticity is unit-free, and marginal product is output per additional input. An option with the wrong unit cannot answer the question even if its arithmetic uses the correct numbers.