A Lab has been asked to evaluate the claim that drinking water in a local restaurant has a lead concentration of 6 parts per billion (ppb). Repeated measurements follow a normal distribution and the population standard deviation is taken to be 0.25 ppb. α = 0.01.
• A sample of three measurements is taken and finds: 6.79; 6.13; 7.17
- Is there evidence to suggest that the lead concentration is different from 6 ppb?
This is a homework question that I'm really stuck on, so if someone could point me in the right direction that would be great.
I realise that it is a hypothesis testing question and that the null hypothesis is that µ = 6 ppb while the alternative is that µ does not equal 6 ppb. However, I really don't know what to do with the three sample measurements. Do I get the mean of the three figures or do I use each in a separate hypothesis test?