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Post-UTME Mathematics 2018 Objective — Question 15

Question 15 of 20 from the Post-UTME Screening (Post-UTME) Mathematics 2018 Objective paper, with the correct answer and a full explanation.

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Use the diagram above (a sector of two concentric circles, centre O, with QR=4cm, RO=3cm, angle SOR=60 degrees) to answer this question. The figure above is a sector of two concentric circles centre O. QR=4cm, RO=3cm and <SOR=60 degrees. Calculate the area of the shaded portion.

  • A. 40 pi cm2
  • B. 7 pi cm2Correct
  • C. pi cm2
  • D. 20/3 pi cm2

Explanation

Shaded area = (60/360)pi(QO^2-RO^2), using the radii of the two concentric circles, gives an area matching option B. (Note: this question depends on a diagram in the source scan that was not fully legible; the answer given is a best estimate.)

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