Question

"N.Y. Lottery Numbers Come Up \(9-1-1\) on \(9 / 11\) " was the headline of an article that appeared in the San Francisco Chronicle (September 13,2002 ). More than 5,600 people had selected the sequence \(9-1-1\) on that date, many more than is typical for that sequence. A professor at the University of Buffalo was quoted as saying, "I'm a bit surprised, but I wouldn't characterize it as bizarre. It's randomness. Every number has the same chance of coming up. People tend to read into these things. I'm sure that whatever numbers come up tonight, they will have some special meaning to someone, somewhere." The New York state lottery uses balls numbered \(0-9\) circulating in three separate bins. One ball is chosen at random from each bin. What is the probability that the sequence \(9-1-1\) would be selected on any particular day?

Short answer

The probability that the sequence \(9-1-1\) would be selected on any particular day is 0.001.

Step-by-step solution

Find the Probability of Drawing Each Number

Since each bin contains 10 balls (numbered 0-9), the probability of drawing a specific number from a single bin is \(\frac{1}{10}\) or 0.1.

Find the Probability of Drawing the Sequence \(9-1-1\)

As each draw is independent, the probability of drawing the sequence \(9-1-1\) would be the product of the probabilities of drawing a \(9\), then a \(1\), then another \(1\). Therefore, the probability is \(0.1 \times 0.1 \times 0.1 = 0.001\).

Key concepts

Independent Events

Understanding the concept of independent events is crucial when dealing with probability. In probability theory, two events are said to be independent if the occurrence of one event does not affect the probability of the occurrence of the other. This means that the outcome of one event has no bearing on the outcome of the second event.

For instance, consider rolling a die and flipping a coin. The result of the die roll does not influence whether the coin will land on heads or tails—they are independent events. Similarly, in the lottery example, the selection of each number is an independent event. The chance of drawing a '9' from the first bin is not impacted by the draw in the second or third bin.

This property allows us to calculate the combined probability of multiple independent events occurring by multiplying their individual probabilities. So, the probability of our desired sequence '9-1-1' happening is simply the product of the probabilities of each number being drawn independently, resulting in \(0.1 \times 0.1 \times 0.1 = 0.001\).

Probability Theory

At the heart of understanding random events is probability theory, which is a branch of mathematics concerned with the analysis of random phenomena. The fundamental component of probability is the 'event', which is any particular outcome or group of outcomes. Probability theory assigns a numerical value, ranging from 0 to 1, to the likelihood of an event occurring.

A probability of 0 indicates an impossibility, whereas a probability of 1 signifies certainty. Any probability in between reflects the degree of certainty that the event will happen. In our lottery problem, the probability of any specific number being drawn from one of the bins is \(\frac{1}{10}\) or 0.1, implying that each number has an equal chance to occur, reflecting the concept of a uniform distribution in this straightforward scenario.

The calculation of complex probabilities relies on rules and theorems developed within probability theory, such as the multiplication rule for independent events, which was utilized in computing the probability of the '9-1-1' sequence.

Randomness in Probability

Randomness is a key concept in probability that refers to the unpredictability and lack of pattern in events. It ensures that each event is governed by chance, with no discernible influence from prior outcomes or external factors.

In the context of the New York state lottery, the random selection of balls mimics the idea of randomness. Because each ball is equally likely to be chosen, every number combination has the same probability of being drawn, demonstrating the concept of a random process.

However, humans often look for patterns and may mistakenly see significance in sequences that are merely the result of random chance, such as the '9-1-1' sequence occurring on September 11th. This tendency is known as apophenia or patternicity, but it does not reflect the underlying principles of randomness where every number has an equal chance to be chosen, regardless of the sequence or date.