Practice question

Question

genetic cross was made between homozygous wild-type males (a ⁺ a ⁺ b ⁺ b ⁺ c ⁺ c ⁺ ) and triple - mutant females (aabbcc) of Drosophila melanogaster. Then the F ₁ males (a ⁺ ab ⁺ bc ⁺ c) were back crossed to the triple-mutant females which resulted in the following F2 progenies: The order of genes as determined from the above data was found to be "b a c" (note that the order is equivalent to "cab" and the order of outside makers are arbitrary). The map distance between "band c" is __ centiMorgan (round off to 1 decimal place).