He drove 123 miles in 2 hours. If you go 100 miles in 2 hours that means you went 50 miles in one hour right? Using the same logic we can convert 123 miles in 2 hours to 61.5 miles per hour and then multiply it by 5.
The parameter in this hypothesis test describes the entire population. So in this test, the parameter is looking into the summary number for instance like an average of all overweights who after undergoing this pattern/daily habits exhibits weight loss.
