NECO 2022 · Paper 1 · Q10

A square of side 10 cm is measured by a student as 9.9 cm. If she uses her measurement to calculate the area of the square, calculate the percentage error.

Worked solution (try it first)
  1. The true area is 102=100 cm210^2 = 100\text{ cm}^2 and the calculated area is 9.92=98.01 cm29.9^2 = 98.01\text{ cm}^2.
  2. The error in the area is 100−98.01=1.99 cm2100 - 98.01 = 1.99\text{ cm}^2.
  3. Percentage error =1.99100×100%=1.99%= \dfrac{1.99}{100} \times 100\% = 1.99\%, option E.

Report a problem with this question