Question

In addition to knowing a person's blood type, it is important to also know whether their Rh factor is positive or negative. The blood types of the first 200 individuals to have their blood drawn at a hospital lab on Monday are recorded below.

	Type
Rh Factor	A	B	AB	O
Positive	61	14	18	77
Negative	9	9	8	16

Find the test statistic. (Round your answer to two decimal places.)

Χ² =  

Calculate the proportion of Rh negative blood types within each of the A, B, AB, and O categories. (Round your answers to three decimal places.)

p̂_A= p̂_B= p̂_AB= p̂_O=

Are these proportions consistent across the categories? Does this support your conclusion in part (a)?

The proportions  ---Select--- are are not consistent across the categories,  ---Select--- refuting confirming our conclusion in part (a).

Answer 1

Observed value
	A	B	AB	O	Total
Positive	61	14	18	77	170
Negative	9	9	8	16	42
Total	70	23	26	93	212

We need to calculate the expected value

The expected value for any cell is calculated by (Row total *Column total)/ Grand Total

So, for cell (1, 1) -> (Positive, A), we can calculate expected value = (170*70)/212 = 56.13

Expected Value
	A	B	AB	O	Total
Positive	56.13207547	18.4434	20.8490566	74.5754717	130.707547
Negative	13.86792453	4.556604	5.150943396	18.4245283	32.2924528
Total	70	23	26	93	163

Calculating chi-square value

calculations
Observed, O	Expected, E	O-E	(O-E)^2	(O-E)^2/E
61	56.13207547	4.867925	23.69668921	0.42215951
14	18.44339623	-4.4434	19.74377002	1.0705062
18	20.8490566	-2.84906	8.117123532	0.3893281
77	74.5754717	2.424528	5.878337487	0.07882401
9	13.86792453	-4.86792	23.69668921	1.70874085
9	4.556603774	4.443396	19.74377002	4.33300129
8	5.150943396	2.849057	8.117123532	1.57585182
16	18.4245283	-2.42453	5.878337487	0.31904955
			X^2=	9.89746133