Three Genes of Corn,R,D,and Y,lie on Chromosome 9 $$\begin{array} { l l l l l } R & 10 & D& 5 & Y \\\hline\end{array}$$

Essay

Three genes of corn,R,D,and Y,lie on chromosome 9.The map of the three genes,using map units is as follows:
$$\begin{array} { l l l l l } R & 10 & D& 5 & Y \\\hline\end{array}$$
In a testcross of a trihybrid plant (R D Y/r d y)arising from true-breeding R D Y/R D Y and r d y/r d y parents,how many R d Y/- d - plants would be expected in a progeny of 1000 if there were no interference? If the coefficient of coincidence were 0.3,how would this change your answer?