Question

A newspaper reports the following changes in the temperature of a city over 4 days:

Answer 1

An average value or a "mean value" is the sum of the data points, divided by how many data points are there.

so, let's do so, but let us convert the decimal amounts to fractions and proceed, notice, there are 4 entries for the temperature change, thus that is our denominator, and our numerator is their sum.

$\bf \cfrac{1.34-\frac{5}{7}-0.75+\frac{4}{9}}{4}\implies \cfrac{\frac{134}{100}-\frac{5}{7}-\frac{075}{100}+\frac{4}{9}}{4} \\\\\\ \textit{we'll use an LCD of 6300}\qquad \cfrac{\frac{8442-4500-4725+2800}{6300}}{4}\implies \cfrac{\frac{2017}{6300}}{4} \\\\\\ \cfrac{\frac{2017}{6300}}{\frac{4}{1}}\implies \cfrac{2017}{6300}\cdot \cfrac{1}{4}\implies \cfrac{2017}{25200}\approx \stackrel{\textit{average daily temperature change}}{0.0800396825396}$