Tag Archives: Probability

Cryptography and Presidential Inaugural Speeches

Given a letter in English, how often does it appear in normal usage of the English language? Some letters appear more often than others. For example, the last letter Z is not common. The vowels are very common because they … Continue reading

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Presidential Elections and Statistical Inference

We use an example of presidential elections to illustrate the reasoning process of statistical inference. The current holder of a political office is called an incumbent. Does being an incumbent give an edge for reelection? The answer seems to be … Continue reading

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Rolling Dice to Buy Gas

The price of gas you pay at the pump is influenced by many factors. One such factor is the price of crude oil in the international petroleum market, which can be highly dependent on global macroeconomic conditions. Why don’t we … Continue reading

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The Middle 80% Is Not 80th Percentile

A student sent me an email about a practice problem involving finding the middle 80% of a normal distribution. The student was confusing the middle 80% of a bell curve with the 80th percentile. The student then tried to answer … Continue reading

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The Osmond Brothers – a Binomial Example

According to Wikipedia, the Osmonds are an American family music group with a long and varied career – a career that took them from singing barbershop music as children, to achieving success as teen-music idols, to producing a hit television … Continue reading

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The Birthdays of the Presidents of the United States

How likely is it to find two people with the same birthday in a group of partygoers? If the group only has 2 or 3 people, it is probably not likely. So how many people do you need to have … Continue reading

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Another look at Titanic passenger data using two-way tables

It is well known that among the passengers in Titanic, women and children were more likely to survive. It is also well known that first class passengers were even more likely to survive than passengers in the other classes. We … Continue reading

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A look at Titanic passenger data using two-way tables

This is an introduction of data analysis for two-way tables using passenger data of the Titanic disaster almost one hundred years ago. The sinking of the Titanic on April 15, 1912 was one of the deadliest peacetime maritime disasters in … Continue reading

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The roulette wheel of fortune

The game of roulette is a wheel of fortune, unfortunately not for you but rather for the casino. Why? Five words – the law of large numbers. The people running the casino know these five words and their implication. They … Continue reading

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One gambling problem that launched modern probability theory

Chevelier de Mere (1607-1684) was a gentleman gambler in France who made it to the history book by turning to Blaise Pascal, an eminent mathematician of his time, for help in finding a mathematical answer for why he consistently lost … Continue reading

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