Michael is buying birthday presents for his five friends. he would like to spend less than $150 total. on average, How much can
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Answer: 151
Step-by-step explanation:
When the prior estimate of population proportion is available , then the formula for sample size:
, where p= prior estimate of population proportion
z*= critical-value.
E= Margin of error.
Let p be the proportion of of girls "wait for their missionary".
p = 11% =0.11
E= ± 0.03
The critical z-value corresponding to 90% confidence level = z*=1.645 [using z-table ]
Substitute all the values in the above formula , we get
Required sample size :
[Rounded to next integer.]
Thus, the number of observations he needs in his sample = 151