Abigail is 8 years older than Cynthia. Twenty years ago Abigail was three times as old as Cynthia

1 answer:

5 0

Abigail would be 32 and Cynthia would be 24 now. Twenty years ago, Abigail was 12, and Cynthia was 4. 12 is 3 times as much as 4, and also 4+8=12.

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An important factor in selling a residential property is the number of times real estate agents show a home. A sample of 23 home

liberstina [14]

Using the t-distribution, it is found that the 95% confidence interval for the mean number of people the houses were shown is (20.1, 27.9).

We have the standard deviation for the sample, hence the t-distribution is used to build the confidence interval. Important information are given by:

Sample mean of $\overline{x} = 24$ .
Sample standard deviation of $s = 9$ .
Sample size of $n = 23$

The confidence interval is:

$\overline{x} \pm t\frac{s}{\sqrt{n}}$

In which t is the critical value for a 95% confidence interval with 23 - 1 = 22 df, thus, looking at a calculator or at the t-table, it is found that t = 2.0739.

Then:

$\overline{x} - t\frac{s}{\sqrt{n}} = 24 - 2.0739\frac{9}{\sqrt{23}} = 20.1$