10.101 The abrasive resistance of rubber is increased by adding a silica filler and a coupling agent to chemically bond the filler to the rubber polymer chains. Fifty specimens of rubber made with a type I coupling agent gave a mean resistance measurement of 92, with the variance of the measurements being 20. Forth specimens of rubber made with a type II coupling agent gave a mean of 98 and a variance of 30 on resistance measurements.

Is there sufficient evidence to say that the mean resistance to abrasion differs for the two coupling agents at the 5% level of significance?