Monday, 29 January 2018

EMPIRE FALLS (RICHARD RUSSO) AND THE PROBABILITY OF INDEPENDENT EVENTS

 “It could be a baby sister.”
His father chuckled, probably at Peanuts. “Mostly boys in our family.”
Then we’re due for a girl,” Miles said.
That’s not how it works. It’s not like flipping a coin.”
What’s it like, then?” It seemed to Miles that it was exactly like flipping a coin, and he didn’t see any reason to let his father skate on such dubious logic just because he was a grown-up.
Max studied him, grinning again, though Miles wished he wouldn’t. “It’s more like rolling dice,” he explained. “Except they don’t have numbers. There’s six sides to a cube, right? In our family ‘boy’ is written on about five sides of the cube. ‘Girl’ is only written on one. So, if you had to bet with your own money, which would you bet on?”
Miles did some calculations. After a minute he said, “How many kids does Uncle Pete have?” His father’s older brother had moved out west—to Phoenix, Arizona—two decades earlier.
Four,” said his father. “All boys.”
Miles nodded. “And you’ve got me.”
You’re a boy too, last time I looked.”
That’s five in a row,” Miles pointed out.
Outside, footsteps sounded on the back porch: Grace, returning from church. Both Miles and his father glanced up at the kitchen window when she passed. This week her bouts of morning sickness had been less severe, and while she wasn’t looking as radiantly beautiful as she had on Martha’s Vineyard, neither did she appear as frightened and despairing as when they’d first returned.
Girl was on the sixth side, right?”




Yes, that´s not how it works. The likelihood of having a boy or a girl is 50% and it doesn´t depend on neither the number of boys you had before nor the amount of them that your uncle has.
According to the law of large numbers, the number of sons will be very close to the number of daughters only if you had a considerable amount of children. But it has to be a huge figure so that the law works.
We all know examples of families with lots of boys since their parents were looking for having a daughter, and they ended up giving up.
Therefore, the chance for the family in the text to have a boy or a girl is 50%. Just like flipping a coin at random.


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