Which of the following cannot be the probability of an event : (A) `2/3` (B) `–1.5` (C) `15%` (D) `0.7`

Answer

To determine which of the given options cannot be the probability of an event, we need to understand the fundamental properties of probability.

### Step-by-Step Solution:

1. **Understand the Range of Probability**:
Probability values must lie between 0 and 1, inclusive. This means that:
- The minimum probability is 0 (impossible event).
- The maximum probability is 1 (certain event).

2. **Evaluate Each Option**:
- **Option (A): `2/3`**
- Convert `2/3` to decimal:
\[ 2/3 \approx 0.6667 \]
- This value lies between 0 and 1, so it is a valid probability.

- **Option (B): `–1.5`**
- This value is negative and clearly less than 0.
- Since probabilities cannot be negative, this cannot be a probability of an event.

- **Option (C): `15%`**
- Convert `15%` to decimal:
\[ 15\% = \frac{15}{100} = 0.15 \]
- This value lies between 0 and 1, so it is a valid probability.

- **Option (D): `0.7`**
- This value is already in decimal form and lies between 0 and 1, so it is a valid probability.

3. **Conclusion**:
- The only option that does not lie within the range of valid probabilities (0 to 1) is **Option (B): `–1.5`**.

### Final Answer:
The probability that cannot be an event is **(B) –1.5**.

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