Question

Which of the following cannot be a probability?

• A. \( \frac{2}{3} \)
• B. 15\%
• C. 0.7
• D. -1.5

Hint:

Probabilities always lie between 0 and 1. Any value less than 0 or greater than 1 is not a valid probability.

Answer 1

The Correct Option is D

Step 1: Understand the concept of probability 
Probability is a measure of the likelihood of an event occurring. The probability of an event is always a number between 0 and 1, inclusive. That is: \[ 0 \leq P(\text{event}) \leq 1 \] A probability of 0 means the event cannot occur. A probability of 1 means the event will certainly occur. 
Step 2: Analyze each option 
Option (1): \( \frac{2}{3} \) is a valid probability, as it is a number between 0 and 1.
Option (2): 15% is equivalent to 0.15, which is a valid probability.
Option (3): 0.7 is a valid probability, as it is between 0 and 1.
Option (4): -1.5 is not a valid probability because probabilities cannot be negative.
Step 3: Conclusion
The only option that cannot be a probability is -1.5, as it falls outside the valid range for probabilities.