Why can't a percent value be written directly as a probability?

Conditions

• The value is intended to represent a probability.

Reasoning, step by step

1. Recall the fundamental rule that probabilities lie in the interval $[0, 1]$.
2. Identify that a percent notation like '10%' corresponds to the number 10, which is greater than 1.
3. Convert the percent to a decimal by dividing by 100 (e.g., $10\% = 0.10$).
4. Use the decimal form as the valid probability.

Example

The speaker warns against entering a percent expression such as 10% as the whole number 10, stating that probability is always between zero and one.

Common misconceptions

• Assuming that '10%' and '0.10' are interchangeable notations for the same mathematical object without conversion.
• Writing a probability as a number greater than 1.

Watch the explanation

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