Tables A telephone exchange operator assumes that 8%8% of the phone calls are wrong numbers. If the operator is correct, what is
1 answer:
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Answer:
Step-by-step explanation:
the mean is given by:
In our case this is:
side note: the main difference between sample mean and population mean is in the 'context'. However, the method to calculate them is the same.
By context I mean: if this the items are taken from some larger category for example: the ages of a few 'students' from a 'class'. Here 'students' are the sample from a larger set that is 'class'. The mean of the 'few students' will be called sample mean. In contrast, if we take the mean of the ages of the whole class then this is called population mean. (population mean == mean of the whole set)
In our case we aren't told exactly where these numbers come from, is this the whole set or a sample from it, the lack of context allows us to assume that the mean can either be population mean or sample mean. So we can safely use any symbol or
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<h3>Answer:</h3>
See the attached
<h3>Step-by-step explanation:</h3>When you square the binomial (a -b), you get ...
... (a -b)² = a² -2ab +b²
That is, both the a² and b² terms have positive signs, and the middle term is twice the product of the roots of the squared terms.
The last two selections have negative signs on the constant, so cannot be perfect square trinomials.
The first selection has a middle term that is -ab, not -2ab, so it is not a perfect square trinomial, either.
The second selection is the correct one:
... 4a² -20a +25 = (2a +5)²