Which of the following cannot be the probability of an event ?

Options

A. 0.8
B. 0.09
C. `-2.3 `
D. `(4)/(5)`

Answer

To determine which of the given options cannot be the probability of an event, we need to recall the fundamental properties of probability. The probability of any event must satisfy the following conditions:

1. The probability of an event is always between 0 and 1, inclusive. This means:
- The minimum value of probability is 0 (impossible event).
- The maximum value of probability is 1 (certain event).

Now, let's analyze each option step by step:

### Step 1: Analyze Option 1 - 0.8
- **Check if 0.8 is between 0 and 1.**
- Since \(0 \leq 0.8 \leq 1\), this value is valid.

### Step 2: Analyze Option 2 - 0.09
- **Check if 0.09 is between 0 and 1.**
- Since \(0 \leq 0.09 \leq 1\), this value is also valid.

### Step 3: Analyze Option 3 - -2.3
- **Check if -2.3 is between 0 and 1.**
- Since \(-2.3 < 0\), this value does not satisfy the probability condition.

### Step 4: Analyze Option 4 - 4/5
- **Convert 4/5 to decimal and check if it is between 0 and 1.**
- \(4/5 = 0.8\)
- Since \(0 \leq 0.8 \leq 1\), this value is valid.

### Conclusion
From the analysis:
- Option 1: Valid (0.8)
- Option 2: Valid (0.09)
- Option 3: Invalid (-2.3)
- Option 4: Valid (0.8)

Thus, the option that **cannot be the probability of an event** is **Option 3: -2.3**.

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