A female heterozygous drosophila melanogaster with the x linked genes of singed bristles (sn), crossveinlesss wings (cv), and vermillion eye colour (v) is testcrossed with a singed, crossveinless, vermillion male and the following progeny were obtained:
1 singed, crossveinless, vermillion 3
2 crossveinless, vermillion 392
3 vermillion 34
4 crossveinless 61
5 singed, crossveinless 32
6 singed, vermillion 65
7 singed 410
8 wildtype 3
total 1000
a) what is the order of these genes on the X chromosome
b) what are the genetic map distances between sn & cv; sn & v; and cv & v
c) what is the coefficient of coincidence