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In Drosophila, the genes for withered wings (whd), smooth abdomen (sm) and speck body (sp) are located on chromosome 2 and are separated by the following map distances:
whd ----------(30.5)----------sm-----(15.5)-----sp
A female with withered wings and a smooth abdomen was mated to a male with a speck body.
The resulting phenotypically wild-type females were mated with males that had the mutant phenotype for all three traits, producing 2000 offspring.
Question: Assume that interference for these genes is 0.3. Calculate the number of observed double crossover progeny. Enter your answer as a whole number, rounded to the nearest integer