Two new mutant lines of a flowering plant have been obtained; one breeds true for blue flower color and the other breeds true for red flower color (wild-type flower color is purple). Consider the following crosses.
1. blue $\times$ purple $\rightarrow \mathrm { F } _ { 1 }$ all purple $\rightarrow \mathrm { F } _ { 2 } 75 \%$ purple; $25 \%$ blue
2. red $\times$ purple $\rightarrow \mathrm { F } _ { 1 }$ all purple $\rightarrow \mathrm { F } _ { 2 } 75 \%$ purple; $25 \%$ red
3. red $\times$ blue $\rightarrow \mathrm { F } _ { 1 }$ all purple

If the purple flower color results from the mixture of red and blue pigments,and all the intermediate products in the pigment pathways are colorless,what phenotypic ratios do you expect in the F₂ of cross 3?