Question Constellation Sign up for free AQA · GCSE · Biology · Higher
Scaling a quadrat sample
The students were given a square quadrat. Figure 2 shows the quadrat.
The total area of the sea shore was 1800 m². The students sampled 2% of the total area of the sea shore. Calculate the number of times the students needed to use the quadrat for the 2% sample. Use your answer from Question 01.2.
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Marking points
- 1 Finds the sampled area as 36 m².
- 2 Divides by the quadrat area and obtains 144, with official error-carried-forward allowances applied where relevant.
Full-mark answer
1800 × 0.02 = 36 m². The quadrat area is 0.25 m², so 36 ÷ 0.25 = 144 times.
Why this answer loses marks
I calculated the sampled area and stopped.
That is only the area to cover; divide it by one quadrat area to obtain the number of placements.