The Data Below Show the Number of Tornadoes Spotted in a Midwestern

Essay

The data below show the number of tornadoes spotted in a midwestern state in the U.S.A.annually before and after 1960.A researcher wants to determine whether there has been a change in the frequency of tornadoes in this state. $$\begin{array} { l | l } 1940 - 1959 & 1960 - 1979 \\\hline 2,2,2,9,4 , & 4,0,1,2,2 \\2,0,1,2,1 , & 1,3,2,4,5 \\2,3,3,5,4 , & 1,2,4,2,1 \\5,2,4,0,4 & 0,2,4,2,2\end{array}$$