The Current (In $\mu A$ ) Necessary to Produce a Certain Level of Brightness of Certain

Essay

The current (in $\mu A$ ) necessary to produce a certain level of brightness of a television tube was measured for two different types of glass and three different types of phosphor, resulting in the accompanying data: $$\begin{array} { l | c c c } \hline & { \text { Phosphor Type } } \\& \mathbf { 1 } & \mathbf { 2 } & \mathbf { 3 } \\\hline \text { Glass 1 } & 280,290,285 & 300,310,295 & 270,285,290 \\\text { Type 2 } & 230,235,240 & 260,240,235 & 220,225,230 \\\hline\end{array}$$ Assuming that both factors are fixed, test $H _ { o A B } \text { versus } H _ { oA B }$ at level .01. Then if $H _ { o A B }$ cannot be rejected, test the two sets of main effect hypotheses.