Question

The standard deviation of some temperature data in °C is 5. If the data were converted into °F, the variance would be:

  1. 81
  2. 57
  3. 36
  4. 25

Answer

  1. 81

Solution:

Given that $\sigma_\text{c}=5$

We know that $\text{C}=\frac{5}{9}(\text{F}-32)$

$\Rightarrow\text{F}=\frac{9\text{C}}{5}+32$

$\therefore\ \sigma_\text{F}=\frac{9}{5}\sigma_\text{c}=\frac{9}{5}\times5=9$

$\therefore\ \sigma^2_{\text{F}}=(9)^2=81$

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