If L = 61, f₁ = 4, f₂ = 3 and h = 10, what is the mode?

Correct answer: c 66.71

61 + 4/(4 + 3) × 10 = 61 + 5.71 = 66.71.

Why the other options are wrong

• a 71.57: 71.57 is a wrong sum; the correction is 4/7 × 10 = 5.71 added to 61.
• b 71.43: 71.43 = 61 + 10.43 is wrong; the correction is 5.71.
• d 65.29: 65.29 = 61 + 4.29 uses f₂/(f₁ + f₂); the formula uses f₁/(f₁ + f₂).