Question on: JAMB Mathematics - 2011

Mode = L₁ + ((\frac{D_1}{D_1 + D_2}))C

D₁ = frequency of modal class - frequency of the class before it

D₁ = 5 - 2 = 3

D₂ = frequency of modal class - frequency of the class that offers it

D₂ = 5 - 3 = 2

L₁ = lower class boundary of the modal class

L₁ = 5 - 5

C is the class width = 8 - 5.5 = 3

Mode = L₁ + ((\frac{D_1}{D_1 + D_2}))C

= 5.5 + (\frac{3}{2 + 3})C

= 5.5 + (\frac{3}{5}) x 3

= 5.5 + (\frac{9}{5})

= 5.5 + 1.8

= 7.3 (\approx) = 7