Question

a runner burns $3.49\times10^{3}\text{ kj}$ during a five - mile run. how many nutritional calories did the runner burn?
$1.46\times10^{1}\text{ cal}$
$8.34\times10^{5}\text{ cal}$
$1.46\times10^{4}\text{ cal}$
$834\text{ cal}$

Explanation:

Step1: Convert kilojoules to kilocalories

We know that \(1\space kcal = 4.184\space kJ\).
Let \(x\) be the number of kilocalories. Then \(x=\frac{3.49\times 10^{3}\space kJ}{4.184\space kJ/kcal}\)

$$x=\frac{3.49\times 10^{3}}{4.184}\space kcal\approx 834\space kcal$$

Answer:

834 Cal