Births really are not evenly distributed across the days of the week. Here are d
ID: 3317814 • Letter: B
Question
Births really are not evenly distributed across the days of the week. Here are data on 600 births in the same locale.
Day
Sun.
Mon.
Tue.
Wed.
Thu.
Fri.
Sat.
Births
88
85
78
73
88
70
118
(a) The null hypothesis is that all days are equally probable. What are the probabilities specified by this null hypothesis? (Round your answer to three decimal places.)
p1 = p2 = . . . = p7 =
What are the expected counts for each day in 600 births? (Round your answer to one decimal place.)
births on each day
(b) Calculate the chi-square statistic for goodness of fit. (Round your answer to one decimal place.)
2 =
(c) What are the degrees of freedom for this statistic?
df =
Do 600 births give significant evidence that births are not equally probable on all days of the week? (Use = 0.05.)
There is no evidence against equal rates of birth for all days of the week.
Births are not equally probable on all days of the week.
Day
Sun.
Mon.
Tue.
Wed.
Thu.
Fri.
Sat.
Births
88
85
78
73
88
70
118
Explanation / Answer
a) p1 = p2 = . . . = p7 = 1/7
expected counts for each day in 600 births =600/7=85.7births on each day
b)
applying chi square goodness of fit test on above data:
2 = 17.75
c)
df =categories-1=7-1 =6
Births are not equally probable on all days of the week.
observed Expected Chi square Probability O E=total*p =(O-E)^2/E sun 1/7 88.000 85.71 0.06 mon 1/7 85.000 85.71 0.01 tue 1/7 78.000 85.71 0.69 wed 1/7 73.000 85.71 1.89 thu 1/7 88.000 85.71 0.06 fri 1/7 70.000 85.71 2.88 sat 1/7 118.000 85.71 12.16 1 600 600 17.7500Related Questions
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