Based on the fact that people will not park illegally if the expected value is negative, the probabilities that would make people stop parking illegally are 26% and 31%.
Expected value can be found as:
= -(Cost of ticket x Probability) + Opportunity cost of searching for parking
Probability of 26% Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Probability of 31%
= -(100 x 26%) + 25 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â = Â -(100 x 31%) + 25 Â Â Â
= -$1 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â = -$6
Probability of 23% Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Probability of 21%
= -(100 x 23%) + 25 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â = Â -(100 x 11%) + 25 Â Â Â
= $2 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â = $4
The probabilities that are negative are: 26% and 31%.
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