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Tossing coins Imagine tossing a fair coin 3 times. (a) What is the sample space for this chance process? (b) What is the assignment of probabilities to outcomes in this sample space?

Short Answer

Expert verified
(a) Sample space: \(\{HHH, HHT, HTH, HTT, THH, THT, TTH, TTT\}\). (b) Each outcome has a probability of 0.125.

Step by step solution

01

Define a fair coin

A fair coin is one that has an equal probability of landing on either heads (H) or tails (T) when tossed. Each outcome, H or T, has a probability of 0.5.
02

Determine possible outcomes for one toss

For one toss, there are two possible outcomes: heads (H) or tails (T). This gives us the sample space for one toss as \( S_1 = \{H, T\} \).
03

Determine the sample space for three tosses

When tossing the coin three times, we consider the outcome of each toss. Each toss can result in either H or T, independent of the others.- First toss: 2 outcomes (H or T)- Second toss: 2 outcomes (H or T)- Third toss: 2 outcomes (H or T)Thus, the total number of outcomes is \(2^3 = 8\).The sample space \(S\) for three tosses is: \(\{HHH, HHT, HTH, HTT, THH, THT, TTH, TTT\}\).
04

Assign probabilities to the sample space outcomes

Since each toss of a fair coin is independent, the probability of any particular sequence is the product of the probabilities of each individual toss.The probability of each outcome (e.g., HHH, HHT, etc.) is \( P( ext{outcome}) = 0.5 \times 0.5 \times 0.5 = 0.125 \).Therefore, each outcome in the sample space \(\{HHH, HHT, HTH, HTT, THH, THT, TTH, TTT\}\) has an equal probability of 0.125.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Sample Space
Imagine tossing a coin multiple times. The sample space is essentially a list of all possible outcomes that might result. For a single toss of a coin, we have two potential outcomes: heads (H) and tails (T). Hence, the sample space for one coin toss is \( S_1 = \{H, T\} \).

When we extend this to three tosses of a coin, we combine each result independently. This means that for each of the three tosses, the outcome can either be H or T. So, the sample space for three tosses becomes a sequence of outcomes. In total, we have \( 2^3 = 8 \) different possible combinations or sequences because each of the three tosses has two possibilities. Therefore, the sample space for three tosses is \( \{HHH, HHT, HTH, HTT, THH, THT, TTH, TTT\} \).

Here are the sequences you might encounter about sample spaces:
  • "HHH" corresponds to all heads.
  • "HTH" implies a head, then a tail, then a head.
  • "TTT" means all tails.
Each outcome listed represents a possible scenario from the experiment.
Independent Events
Independent events are events that do not influence each other. This is significant when considering multiple tosses of a coin. If we are tossing a fair coin more than once, each toss is independent of the previous ones. The result of one toss does not affect the outcome of the next toss.

For example, if you toss a coin and it lands on heads, the probability of heads on the next toss is still the same: 0.5. This independence allows us to calculate the probability of outcomes across multiple events by multiplying the probabilities of each independent event.

In our exercise, there are three tosses of the coin. Each toss is independent from the others, meaning each outcome, H or T, remains equally probable regardless of previous results. Hence, the probability of getting any particular sequence is computed by multiplying the probabilities for each toss: \( P(\text{sequence}) = 0.5 \times 0.5 \times 0.5 = 0.125 \).
Understanding this concept helps in scenarios where independent events occur, such as rolling a die, picking a card from a shuffled deck multiple times without replacement, etc.
Fair Coin
A fair coin is a fundamental concept in probability. It is a simple, unbiased mechanism where there are only two possible outcomes: heads (H) or tails (T). Each outcome, whether heads or tails, has an equal likelihood of occurring. That makes the probability of either landing at 0.5, or \( P(H) = 0.5 \) and \( P(T) = 0.5 \).

This fairness is an assumption used in exercises and experiments involving coin tosses, ensuring that the outcomes are completely random and not skewed in favor of one result. This assumption is crucial when calculating probabilities over multiple events because it guarantees equal chances, allowing precise mathematical modeling of the situation.

Knowing how a fair coin operates is foundational for understanding more complex probability scenarios, as it provides a simple example of symmetry and balance between outcomes.
Outcome Probability
Outcome probability refers to the likelihood of a specific result from a chance process. When dealing with a fair coin, each toss is a random event with two possible outcomes. If we toss the coin three times, we need to calculate the probability that any specific outcome occurs.

Since each outcome from our sample space in a three-toss scenario has the same probability due to the fairness of the coin and independence of each toss, we use multiplication. The probability for any one sequence is determined as follows: \( P(\text{outcome}) = 0.5 \times 0.5 \times 0.5 = 0.125 \).

This means that each of the sequences in the sample space (e.g., HHH, HHT, HTH, etc.) has an equal probability of occurring: 0.125. This uniform assignment of probability is typical for independent, fair events, as it distributes the likelihood equally across all potential outcomes. Understanding outcome probability aids in tackling more complex probability models, such as those involving dice, spinners, or card games.

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