Question

A rainy day occurs once in every 10 days. Half of the rainy days produce rainbows. What percent of all the days do not produce rainbow?

• A. 95%
• B. 10%
• C. 50%
• D. 5%

Answer 1

The Correct Option is A

To determine what percent of all days do not produce a rainbow, we follow these steps:

1. Calculate the probability of a rainy day: There is 1 rainy day every 10 days, so the probability of a rainy day is 1/10 or 10%.
2. Calculate the probability of a rainy day producing a rainbow: Since half of the rainy days produce rainbows, the probability of a rainy day producing a rainbow is (1/2) * 10% = 5%.
3. Determine the probability of a day resulting in any rainbows: Only rainy days have rainbows, so the probability of having rainbows on any given day is 5%.
4. Calculation of the complement or days without a rainbow: If 5% of days have a rainbow, the remaining days do not. Therefore, 100% - 5% = 95% of all days do not produce a rainbow.

Therefore, the percent of all days that do not produce a rainbow is 95%.