Biology a level help

Help
Help I don’t get how to do this… the correct answer is 2000 as it’s says on the paper but I don’t get how.
I got 2000000
I did:
10:90 (10+90=100)

basically this q^

(edited 11 months ago)

Reply 1

humble heroics

Can you show the full question please?

Reply 2

Alevelhelp.1

Original post by humble heroics

Can you show the full question please?

It’s work out the original number of bacteria in the sample

Reply 3

humble heroics

Each dilution is 1:10 so working backwards: 2 x 10 = 20 (1st dilution), 20 x 10 = 200 (2nd dilution), 200 x 10 = 2000 (3rd dilution)

Reply 4

Alevelhelp.1

Original post by humble heroics

Each dilution is 1:10 so working backwards: 2 x 10 = 20 (1st dilution), 20 x 10 = 200 (2nd dilution), 200 x 10 = 2000 (3rd dilution)

Ahh so that ratio we cancel down ok thanksss

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