Maths Skills in Biology

Approximately 10% of the total marks in Edexcel GCSE Biology require mathematical skills. That means around 20 marks across both papers are maths-based. These are often straightforward calculations, but students regularly lose marks by not showing working, forgetting units, or making conversion errors.

This lesson covers every type of mathematical skill you need for the exam.

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Calculating Means

The mean (average) is the most commonly required calculation.

Formula: Mean = sum of all values ÷ number of values

Example: A student measured the height of seedlings (in cm): 4.2, 3.8, 4.5, 4.1, 3.9

Mean = (4.2 + 3.8 + 4.5 + 4.1 + 3.9) ÷ 5 = 20.5 ÷ 5 = 4.1 cm

Exam tip: If there is an anomalous result (a value that does not fit the pattern), you should exclude it from the mean calculation and state that you have done so.

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Percentages

Calculating a Percentage

Formula: Percentage = (part ÷ total) × 100

Example: Out of 250 students, 45 have brown eyes. What percentage have brown eyes?

(45 ÷ 250) × 100 = 18%

Calculating a Percentage of an Amount