Answer:
Step-by-step explanation:
n = 400
Proportion p = 229/400= 0.5725
For 95% confidence interval we use Z value as 1.96
Std error = 0.025
margin of error = 1.96*0.025
Confidence interval 95% = 0.5725±Margin of error
= (0.524, 0.621)
b) When smiled x becomes 277
p = 0.6925
Std error = 0.023
Margin of error= 1.96*0.023
Confidence interval = (0.647, 0.738)
Smiling increases the chances of stopping since mean and conidence interval bounds are showing increasing trend.
Answer:
B.
Step-by-step explanation:
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