RAS Prelims: Concepts and Practice

Learning outcome

You can mark the unstated idea a statement needs, and reject an extra prediction.

Concepts and why

An assumption is an idea the statement uses but does not say. Without that idea, the statement would not be made. A restatement only repeats the sentence, so it is not a hidden assumption. A new prediction, such as a prize, a crowd or a future record, is not an assumption unless the statement cannot stand without it.

Worked examples

Statement: The city will run extra buses during the fair so that visitors can travel. Needed idea: Visitors will need a way to travel during the fair. The purpose of the extra buses needs that idea. Not needed: The fair will be the largest in the state. The statement can stand without that claim. Not needed: Bus fares will fall. The statement does not depend on the fare.

Common mistakes

Choosing the biggest or most attractive claim. Choosing a sentence that only repeats the statement. Treating a possible result as an assumption when the statement does not need it.

Practice questions

1. Statement: Carry an umbrella because the sky is dark. Which idea is needed?

A dark sky can bring rain. Or: the person owns two umbrellas.

2. Statement: The school added a late bus so that students in the last class can go home. Which idea is needed?

Some students in the last class need that bus to go home. Or: the late bus will always be full.

Answers and explanations

1. A dark sky can bring rain. The reason for carrying the umbrella needs that idea. Owning two umbrellas is an extra fact.
2. Some students in the last class need that bus to go home. A bus that is always full is a prediction the statement does not need.

Analogy

A cook says the pot needs a lid so the water will stay hot. The needed idea is that a lid helps the water stay hot. The cook did not assume that this pot is the largest in the shop.

Quick reference

Keep the idea the statement cannot do without. Drop a repeat. Drop a new prediction.