Solved Problem on Temperature
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In the Sahara desert, the temperature of X °C was recorded. If the scale used had been Fahrenheit, the reading would be 72 units higher. Determine the value of these temperatures.


Problem data:
  • Temperature in the Celsius scale:    tC = X °C;
  • Temperature on the Fahrenheit scale:    tF = tC+72 °F.
Solution

The equation for converting temperatures into the Celsius and Fahrenheit scales is given by
\[ \begin{gather} \bbox[#99CCFF,10px] {\frac{t_{C}}{5}=\frac{t_{F}-32}{9}} \end{gather} \]
substituting the values given in the problem
\[ \begin{gather} \frac{X}{5}=\frac{X+72-32}{9}\\[5pt] 9X=5(X+40)\\[5pt] 9X=5X+200\\[5pt] 9X-5X=200\\[5pt] 4X=200\\[5pt] X=\frac{200}{4}\\[5pt] X=50°C \end{gather} \]
\[ \begin{gather} \bbox[#FFCCCC,10px] {t_{C}=50\;\text{°C}} \end{gather} \]
substituting this value in the relationship between the temperatures given in the problem
\[ \begin{gather} t_{F}=t_{C}+72\\[5pt] t_{F}=50+72 \end{gather} \]
\[ \begin{gather} \bbox[#FFCCCC,10px] {t_{F}=122\;\text{°F}} \end{gather} \]
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