WAEC Mathematics 2023 Theory — Question 9

Model answer

(a) Total number of trees=4+6+4+5+6+2=27 trees. Median position=(n+1)/2=(27+1)/2=14th position. Counting through the cumulative frequency, the median height=5 m. (b)(i) Mean=Σfx/Σf=144/27≈5.3 m (using Σfx=144 and Σf=27 from the frequency table). (ii) Standard deviation δ=√[(Σfx²/Σf)-(Σfx/Σf)²]=√[(834/27)-(144/27)²]=√(30.89-28.44)=√2.297≈1.6 (1 d.p.).