Problem #22: Meteorology

It rains here one day out of three. Our local meteorologists, who are pessimistic by nature, are wrong in their daily forecasts one time out of two when they should have predicted good weather but wrong only one time out of five when they should have forecasted rain.

Each morning, Francine leaves home for the day. If she departs without an umbrella and it rains, she is twice as annoyed as if it had been fair and she had taken her umbrella with her. "Would I be wiser," she wonders, "to listen to the morning weather forecast and take my umbrella only if rain is predicted? Or should I consistently carry it? Or should I never take it? What would you advise Francine to do?

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