Question 3

An environmental scientist carries out a serial dilution of a water sample from a local lake to estimate the population of a specific green alga (Chlorella).

The scientist uses the following method:

Transfer $cm35\text{ cm}^3$ of the lake water from an original sample of $cm3120\text{ cm}^3$ to a clean beaker.
Carry out four 5-fold serial dilutions. Each dilution involves transferring $cm32\text{ cm}^3$ of the solution to a test tube containing $cm38\text{ cm}^3$ of sterile distilled water.
Transfer $cm30.2\text{ cm}^3$ of the final diluted solution to a microscope counting chamber.
Count the algal cells under a microscope.

The scientist counts 48 algal cells in the counting chamber.

Calculate the total number of algal cells in the original $cm3120\text{ cm}^3$ lake water sample. Assume the cells are distributed uniformly and that each counted cell represents a single individual in the diluted volume. Give your answer in standard form.