Parcel masses X X\,X kg are modelled by X∼N(2.2,0.32)X\sim N(2.2,0.3^2)X∼N(2.2,0.32). A worker selects 20 parcels in December and records a total mass of 46 kg.
Find the sample mean.
Test at the 5% significance level whether the population mean mass is greater in December, assuming the variance is unchanged.
State one limitation of the test.
328 exam-style questions on WJEC A Level Maths 4.2 Statistical distributions (A-level only), covering 4.2.1 Statistical distributions (A-level only), 4.2.2 Statistical distributions (A-level only), and 4.2.3 Statistical distributions (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.