Please explain In a Drosophila dihybrid cross a sepia male w

Please explain

In a Drosophila dihybrid cross, a sepia male was mated to a apterous female. Their phenotypically wild F_1 female produced the following offspring when crossed to phenotypically wild F_1 males: Please set up a null hypothesis and use a Chi-square analysis to see if the observation follows the Mendelian phenotypic ratio.

Solution

Answer:

Chi-Square value= 1.33

The degrees of freedom = 4-1 = 3

The probability level for df 3

Chi-Square value, 1.33 lies below 0.5 (probability), so we fail to reject null hypothesis.

Phenotype	Observed(O)	Expected (E)	O-E	(O-E)2	(O-E)2/E
Wild type	450	450	0	0.00	0.00
Sepia	160	150	10	100.00	0.67
Apterous	140	150	-10	100.00	0.67
sepia/aprerous	50	50	0	0.00	0.00
	800	800			1.33