Question

Marshall stability tests of bituminous mixtures from two suppliers A and B are summarized in the following table. Can it be concluded that suppliers obtain, on average, the same results at the 5% significance level? State and test your assumptions as much as possible.

Supplier A
Number of observations = 31
Average (kN) = 20.2
Standard deviation (kN) = 4.8

Supplier B
Number of observations = 16
Average (kN) = 24.2
Standard deviation (kN) = 5.4

Answer 1