WAEC 2023 · Paper 1 · Q20

Approximation & error

A notebook of length $15\text{ cm}$ was measured to be $16.8\text{ cm}$ . Calculate, correct to two decimal places, the percentage error in the measurement.

Worked solution (try it first)

The error is $16.8 - 15 = 1.8$ cm.
Divide by the true length and multiply by 100: $\frac{1.8}{15} \times 100\% = 0.12 \times 100\%$ .
So the percentage error is 12.00%, option A.

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