The probability of an event not happening is the complement of the probability of the event happening. The formula for the complement is:

$P(\text{not happening}) = 1 - P(\text{happening})$

Given the probability of the event happening is $\frac{28}{83}$, we find the probability of it not happening by subtracting this from 1:

$P(\text{not happening}) = 1 - \frac{28}{83}$

To subtract, express 1 as $\frac{83}{83}$:

$P(\text{not happening}) = \frac{83}{83} - \frac{28}{83} = \frac{83 - 28}{83} = \frac{55}{83}$

Thus, the probability of the event not happening is:

$\frac{55}{83}$

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Here are 5 related questions:

1. What is the complement rule in probability?
2. How do you calculate the probability of two independent events not happening?
3. If the probability of an event is given as a percentage, how can you convert it to a fraction?
4. What is the sum of probabilities of all possible outcomes in a sample space?
5. How does conditional probability affect the calculation of the complement?

Tip: Always ensure probabilities are expressed in the same form (fractions or decimals) when performing operations on them.