Estimation and Approximation

Estimation is arguably the single most powerful strategy for the UCAT Quantitative Reasoning subtest. On many questions, you do not need to calculate the exact answer — you need to calculate an answer that is close enough to distinguish between the four options. This lesson teaches you when and how to estimate effectively.

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Why Estimation Works in UCAT QR

The QR subtest is multiple choice with four options. The question designers must make the wrong options plausible, but they cannot make all four options extremely close together (otherwise the question would be unfairly difficult). In practice, the options are usually spread across a meaningful range.

Example options: A) 145 B) 290 C) 435 D) 580

These options are roughly 145 apart. An estimate accurate to within ±50 would identify the correct answer with certainty.

Example options: A) 12.3% B) 18.7% C) 24.1% D) 31.5%

These differ by about 6 percentage points. An estimate accurate to within ±3% would suffice.

Key Principle: You do not need the exact answer. You need an answer accurate enough to be closer to the correct option than to any other option.

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