Which of the following cannot be the probability of an event?
Explanation
Option (B) is the correct answer because the probability of an event must always lie between 0 and 1, inclusive. The provided context explicitly states that for any event E, the probability P(E) satisfies the inequality 0 P(E) 1. Since -1.5 is a negative number (less than 0), it falls outside this permissible range and therefore cannot represent the probability of an event. Options (A), (C), and (D) are valid probabilities as 2/3 0.67, 15% = 0.15, and 0.7 all lie within the range [0, 1].
Solution Steps
Step 1: Identify the range of probability from the context: The probability of an event E is a number P(E) such that 0 P(E) 1.
Step 2: Analyze Option (A): 2/3 is approximately 0.67. Since 0 0.67 1, it is a valid probability.
Step 3: Analyze Option (B): -1.5 is less than 0. Since probability cannot be negative, it cannot be the probability of an event.
Step 4: Analyze Option (C): 15% is equal to 15/100 or 0.15. Since 0 0.15 1, it is a valid probability.
Step 5: Analyze Option (D): 0.7 lies between 0 and 1. Thus, it is a valid probability.
Step 6: Conclude that -1.5 is the only value that violates the condition 0 P(E) 1.