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    • Thread Starter


    This is for my biology practice paper, and I may work this out myself in due time, but I'm sat here trying to workout this maths question on it. I have the answer in-front of me - but I cannot see how you get to this figure. Can someone explain it to me?

    Doctors investigated the accuracy of two methods, A and B, used to measure sperm counts.They obtained samples of semen from 500 men. They used both methods to obtain a spermcount for each sample.
    • Method A required the semen to be diluted by a factor of 2 before counting.• Method B required dilution by a factor of 20.

    Method B involved counting the number of sperm cells seen in small squares on aspecial glass microscope slide. Each square contained 0.25 × 10^–6 cm3 semen. Forone diluted sample of semen, the mean number of sperm cells per square was 1.05.Calculate the mean number of sperm cells per cm3 of semen. Show your working

    Probably won't get a question like this on my exam paper - but I would feel the better for having a firmer understanding on the working-out.
    • Thread Starter

    It's okay - I worked it out.

    Divide - 1/0.25 × 10^–6 cm3 ...x 20. Then x 1.05. = 84 x 10^6.

    It's because I hadn't figured out the first division.

    It's a shame I wouldn't get 20-mins in an exam to get my head around this...but then again, it is 7am. (need more coffee, perhaps).
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