I've been asked to calculate how many women are in our company UK office and compare it to the most recent UK census data. The figures below are just for example purposes:

**UK - My company:**

400 women / 800 men; 33.34% of company are women.

**UK - Census (working population):**

33,000,000 women / 34,000,000 men; 49.25% of uk working population are women.

I now want to know if my company is

**underrepresented by women compared to the census data, or not. E.g. if my company had 48% women then I would assume this finding isn't significant and down to natural variation in distribution. However, if it was 10%, then that would presumably be a significant finding.**

*significantly*So my question is - what's the method to use for determining at what % the difference becomes significant or not?

I think I have to use a t-test or something, but I haven't done that in ages, so could someone please walk me through the calculation and any assumptions using the above example data?

Thank you