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Scrabble In the game of Scrabble, each player begins by drawing 7 tiles from a bag containing 100 tiles. There are 42 vowels, 56 consonants, and 2 blank tiles in the bag. Cait chooses her 7 tiles and is surprised to discover that all of them are vowels. Can we use a binomial distribution to approximate this probability? Justify your answer.

Short Answer

Expert verified
Yes, we can approximate with a binomial distribution if assuming near-constant probability and large population approximation assumptions.

Step by step solution

01

Identify the Characteristics of a Binomial Distribution

To use a binomial distribution, an experiment must have a fixed number of independent trials, each with two possible outcomes: success or failure. The probability of success must be consistent in each trial. In this scenario, each tile can either be a vowel (success) or not (failure). We draw 7 tiles, which are independent trials if drawn back-to-back without replacement; however, the probability of drawing a vowel changes in each draw since the tiles aren't replaced (typically requiring clarification for binomial assumption).
02

Define the Parameters for Comparison

The number of trials, \( n \), is 7. The probability of drawing a vowel initially, \( p \), is \( \frac{42}{100} = 0.42 \). For a binomial distribution approximation, we assume each draw is approximately independent, and the probability \( p \) should remain roughly constant, which isn't strictly true without replacement unless treated as approximately true for a large population relative to sample size.
03

Check for Large Population Assumption

The bag begins with 100 tiles, meaning a small change when drawing a few tiles is approximated. Given that 93% is still remaining if considering consecutive draws without replacement (for theoretical j), approximation can sometimes be done using the binomial model provided bag is sufficiently large.
04

Determine Feasibility of Using Binomial Model

Though the probability changes as we remove tiles, assuming the fraction of vowels relative to the total remains nearly consistent along all draws, it can allow approximation with binomial distribution for simplicity, despite theoretical issues depending population size.

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Key Concepts

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

Probability in Scrabble Tile Drawing
Probability refers to the measure of the likelihood of a particular outcome or set of outcomes. In the Scrabble tile drawing problem, we are interested in the probability that all 7 tiles Cait draws are vowels from a set of 100 tiles. Each draw can be considered one trial in our experiment. The probability of an event is calculated as the number of favorable outcomes divided by the total number of possible outcomes.
For Cait, the probability of drawing a vowel on her first pick is fairly simple. Out of 100 tiles, 42 are vowels, providing a probability of \( \frac{42}{100} = 0.42 \).
However, calculating the probability for all 7 tiles to be vowels becomes complicated because the probability changes slightly with each tile drawn due to the lack of replacement. This commonly requires a slightly different treatment if precision is vital, but for larger sets like 100 tiles, approximation techniques often help manage this complexity.
Understanding Independent Trials
Independent trials in probability involve scenarios where the outcome of one trial does not affect the outcome of another. In our context, drawing tiles from a Scrabble bag without replacement technically makes the trials dependent because each draw changes the makeup of the remaining tiles.

However, when dealing with a large enough population, such as 100 tiles in a bag, each individual tile's influence is relatively small. Thus, we can sometimes assume each draw as approximately independent, which simplifies calculations significantly. This approximation is fundamental when trying to apply a binomial distribution in this context, as it assumes consistent probabilities through trials.
Thus, even in non-ideal conditions where exact independence isn’t feasible, practical approximation can provide useful insights into possible outcomes.
The Role of Vowels in a Binomial Model
Vowels, in the case of the Scrabble problem, are defined as the 'successes' in a binomial distribution model, where each draw has the potential to be a vowel (success) or not (failure). In Cait's scenario, we have a fixed number of trials, namely 7 draws. Our initial probability of drawing a vowel is \( 0.42 \), which changes slightly due to the lack of replacement after each draw.

The binomial distribution helps us model the number of times we draw a vowel over several trials, assuming approximation for ease. A binomial distribution is used where each trial is thought to have the same probability of success, thus enabling predicted outcomes such as the count of vowels drawn amongst the total draws.
Scrabble and Tile Drawing
In Scrabble, strategy and randomness mix in interesting ways, especially when considering drawing from the large tile pool. Each player starts with seven tiles, drawn randomly, dictating early game options.

The tiles include a mix of vowels, consonants, and blanks, leading to diverse word-building opportunities. With 100 tiles, players get a mere glimpse of what’s available at any time. Probability theory, especially when approximated using binomial distributions, provides insights into the likelihood of various draws, offering players a statistical sense of the letters they might expect.
Closing these gaps with statistical unfairness brought through strategic choices enriches the game’s complexity – where probability paints a backdrop, the player's tactic adds color.

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Most popular questions from this chapter

Keno Keno is a favorite game in casinos, and similar games are popular with the states that operate lotteries. Balls numbered 1 to 80 are tumbled in a machine as the bets are placed, then 20 of the balls are chosen at random. Players select numbers by marking a card. The simplest of the many wagers available is "Mark l Number." Your payoff is \(\$ 3\) on a \(\$ 1\) bet if the number you select is one of those chosen. Because 20 of 80 numbers are chosen, your probability of winning is \(20 / 80,\) or \(0.25 .\) Let \(X=\) the net amount you gain on a single play of the game.

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Aircraft engines Engineers define reliability as the probability that an item will perform its function under specific conditions for a specific period of time. A certain model of aircraft engine is designed so that each engine has probability 0.999 of performing properly for an hour of flight. Company engineers test an \(\mathrm{SRS}\) of 350 engines of this model. Let \(\bar{X}=\) the number that operate for an hour without failure. (a) Explain why \(X\) is a binomial random variable. (b) Find the mean and standard deviation of \(X .\) Interpret each value in context. (c) Two engines failed the test. Are you convinced that this model of engine is less reliable than it's supposed to be? Compute \(P(X \leq 348)\) and use the result to justify your answer.

Marti decides to keep placing a \(\$ 1\) bet on number 15 in consecutive spins of a roulette wheel until she wins. On any spin, there's a 1 -in- 38 chance that the ball will land in the 15 slot. (a) How many spins do you expect it to take until Marti wins? Justify your answer. (b) Would you be surprised if Marti won in 3 or fewer spins? Compute an appropriate probability to support your answer.

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