Probability and Baby Blues


[Photo by audi_insperation.]

[In The Birthday Surprise, Alex discovered her family was expecting a new member…]

What will the baby look like, Alex wondered. “Dad, is there any way to tell whether the baby will have blue eyes like I do, or brown like the rest of the family?”

Dr. Jones shuffled the papers on his desk and found a blank page. “Over 100 years ago, the Austrian monk Gregor Mendel studied genetics, or how various traits are passed down from one generation to another.” He began to draw a diagram as he talked.

Continue reading Probability and Baby Blues

Alexandria Jones and the Birthday Surprise

[Photo by D Sharon Pruitt.]

[July 27th is Alex’s birthday, which she shares with Johann Bernoulli, an irascible mathematician from the late 17th century.]

The guests had gone. Alex and her family sat around the table, sharing the last tidbits of birthday cake and ice cream. Alex smiled at her parents.

“Thanks, Mom and Dad,” she said. “It was a great party.”

Maria Jones, Alex’s mother, leaned back in her chair. “I do have one more surprise for you, Alex. But you will have to share this one with the whole family.”

Leon groaned. “I know what it is: Let’s all pitch in to clean up.”

“That wouldn’t be a surprise,” Alex said.

Continue reading Alexandria Jones and the Birthday Surprise

Quotations XXIV: Probability


[Photo by Micah Sittig.]

I used to fill the margins of my math newsletter with quotations and tidbits of math history. Here are some quotes from the July/August 1999 issue on probability, along with a few others I’ve stumbled on while browsing the internet.

No knowledge of probabilities helps us to know what conclusions are true. There is no direct relation between the truth of a proposition and its probability.

John Maynard Keynes

The 50-50-90 rule: Anytime you have a 50-50 chance of getting something right, there’s a 90% probability you’ll get it wrong.

Andy Rooney

Continue reading Quotations XXIV: Probability

A Little Bit of This, a Little Bit of That…

funny pictures of cats with captions

It’s high time I got back on track with my Alexandria Jones posts, so I’ve been working hard on a short introduction to probability, to go along with The Birthday Surprise. Or, more honestly, I’ve been procrastinating on a short intro … well, anyway, here’s a little of what I’ve been reading around the interwebs lately.

Continue reading A Little Bit of This, a Little Bit of That…

Math Teachers at Play #28 via CTK Insights

There’s plenty to enjoy at this month’s Math Teachers at Play blog carnival. Check it out:

This is a Math teachers at play carnival, issue #…which I am going to reveal shortly. See if you can make it from what is known as a single image stereogram. Try focusing your eyes behind the screen.

In this month’s issue: What is the number of this issue? … Sad news … Interesting and relevant news … From the trenches … Math curiosities … Jokes … P.S. … Read more

via CTK Insights

Mathematics and Multimedia Blog Carnival #1

The new math carnival is up, and it’s a good one. Check it out!

Also, remember that Wednesday’s the deadline to send in your submission for the Math Teachers at Play carnival, coming this Friday now posted at CTK Insights.

Mathematics and Multimedia Blog Carnival #1 THE NUMBER 1 Welcome to the Mathematics and Multimedia Blog Carnival Number 1. Before beginning, let us see what's so special about 1 as a number. is a homophone of Juan (dela Cruz), the person who represents the Filipino people.  He is just like Uncle Sam of the United States. Hmmm… just a thought, should we change Juan dela Cruz to Manny Pacquiao? is the multiplicative identity. Any number multiplied by 1 is equal to that number. is the only … Read More

via Mathematics and Multimedia

Congratulations, Kitten!

[Photo by dougwoods.]

Today is my daughter Princess Kitten’s blogiversary. Check out her post:

And then take some time to browse her blog. I think you’ll enjoy her stories. She’s even written a few things about math:

[Update: I just noticed that this is the 500th post to be published on Let’s Play Math! blog. Wow! I guess Kitten and I will both be celebrating today…]


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