# Serial Dilution Calculations watch

1. I'm terrible at maths and so I can't get my head around this calculation.

Dilute 5 uL of blood 1:2000 with solution Y.

All I can come up with is:

1:2000

.:. 5uL : 10,000uL

.:. add 10mL of solution Y?

But apparently we're meant to do serial dilutions which I've never understood.

I would really appreciate help with this topic.

Edit: I've had a quick Google and attempted it so that you guys know I'm not trying to get someone to do my homework for me lol. This is what I have but no idea if it's correct

- Test tube 1: Add 19uL solution Y and 1uL blood to produce 1:20 dilution
- Test tube 2: Take 1uL from test tube 1 and add to 19uL solution Y to produce 1:200 dilution
- Test tube 3: Take 1uL from test tube 1 and add to 19uL solution Y to produce 1:2000 dilution

Is this correct?

Thank you.
2. Yes, this is correct. Serial dilutions work in powers of 10, to keep the maths simple.
3. (Original post by Sparkliest)
I'm terrible at maths and so I can't get my head around this calculation.

Dilute 5 uL of blood 1:2000 with solution Y.

All I can come up with is:

1:2000

.:. 5uL : 10,000uL

.:. add 10mL of solution Y?

But apparently we're meant to do serial dilutions which I've never understood.

I would really appreciate help with this topic.

Edit: I've had a quick Google and attempted it so that you guys know I'm not trying to get someone to do my homework for me lol. This is what I have but no idea if it's correct

- Test tube 1: Add 19uL solution Y and 1uL blood to produce 1:20 dilution
- Test tube 2: Take 1uL from test tube 1 and add to 19uL solution Y to produce 1:200 dilution
- Test tube 3: Take 1uL from test tube 1 and add to 19uL solution Y to produce 1:2000 dilution

Is this correct?

Thank you.
Your first step is correct to reach a 1/20 dilution. But then both subsequent steps are diluting 20x so you reach 1/400 and then 1/8000 respectively. You need to dilute by 20x once and 10x twice. (Or whatever other numbers you choose... as long as the product is 2000).

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: February 5, 2017
Today on TSR

### Edexcel C4 Maths Unofficial Markscheme

Find out how you've done here

### 2,099

students online now

Exam discussions

### Find your exam discussion here

Poll
Useful resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE