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# Can someone please explain these questions to me? (Biology A2) Watch

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1. Explain why it might sometimes be more appropriate to use systematic sampling? (3marks)

A microscope slide of human blood may contain thousands of red blood cells, how could you use random sampling to estimate the number of cells in 1cm3 of blood (4 marks)
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3. (Original post by Weronika_m)
Explain why it might sometimes be more appropriate to use systematic sampling? (3marks)

A microscope slide of human blood may contain thousands of red blood cells, how could you use random sampling to estimate the number of cells in 1cm3 of blood (4 marks)
1. Systematic sampling is when samples are taken from a large population in relation to a fixed point. This may be more appropriate where there are limits on time, money and resources for the investigation.

2. Split the slide into a grid and use a number generator to select 3 random 1cm^3 coordinates. Count the blood cells in those coordinates and find an average. Repeat this 3 times, keeping the source, thickness and microscope the same.

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