Question

according to a census, 7.1% of all babies born are of low birth weight. An obstetrician wanted to know whether mothers between the ages of 35 and 39 yesrs give birth to a higher percentage of low- birth- weight babies. she randomly selected 240 births for which the mother was 35 to 39 years old and found 28 low- birth - weight babies complete parts a-c

(a) If the proportion of low bwh weight babies for mothers in this age group is 0.071.compute the expected number of low birth weight births to 35-40 39-year-old mothers. What is the expected number of birth to mothers 35 to 39 years old that are not low bith weight? The expected number of our bith weight bittes to 35-16 39 year old mothers is The expected number of birth to mothers 35 to 39 years old that are not low birth weight is (Type integers or decimals) Answer the chutian's question at the 2016 kvel el significance using the chi square goodness of the State the null and alumnative hypotheses for this tout Hy 10071 WOT Use technology to complete for this test Use the Tech button for further (Round to be decimal places as needed)

Answer 1

expected number of low birth weight =np=240*0.071 =17.04

expected number of not low birth weight =np=240*0.071 =240*(1-0.071)=222.96

b)

null Hypothesis:              Ho:   p=		0.071
alternate Hypothesis:    Ha: p ≠		0.071

applying chi square goodness of fit test:

	relative	observed	Expected	residual	Chi square
Category	frequency(p)	Oi	Ei=total*p	R2i=(Oi-Ei)/√Ei	R2i=(Oi-Ei)2/Ei
1	0.071	28	17.04	2.655	7.049
2	0.929	212	222.96	-0.734	0.539
total	1.00	240	240	1.921066958	7.59
test statistic X2=		7.588

p value =

0.006

from excel: chidist(7.588,1)

option A is correct

c)

null Hypothesis:              Ho:   p=		0.071
alternate Hypothesis:    Ha: p ≠		0.071

p value =

0.006

option B is correct