James is twice as old as Hannah. Four years from now, the sum of their ages will be 41. How old are they now?
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Answer:
The statement that "the margin of error was given as percentage points" means that the population proportion is estimated to be with a certain level of confidence, within the interval
; where
is likely to contain the true population percentage of people that prefer chocolate pie.
Step-by-step explanation:
The margin of error for proportions is given by the following formula:
Where:
is the critical value that corresponds to the confidence level; the confidence level being
,
is the sample's proportion of successes,
is the size of the sample.
In this exercise we have that and that the margin of error is 0.05.
Therefore if we replace in the formula to calculate the confidence interval we get:
Which means that the true population proportion is estimated to be, with a certain confidence level, within the interval (0.09, 0.19).
