Brain Teaser: What shirt size you need?

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You have been invit­ed to a fundrais­ing gala at your old col­lege (via Zoom of course) and decide that this black-tie event demands a super white Ital­ian shirt, like the one you bought years ago for your wedding.

When you find and brave­ly try the wed­ding shirt on (size 16), your wife notices that the col­lar suf­fo­cates you — you DO need about 1/4″ more space every­where in-between your neck and the col­lar all around your neck.

So you’ll need a new shirt.

What size shirt do you need to buy? 

PS1: In case you don’t know, shirt size 16 means that a tape wrapped around your neck and two fin­gers posi­tioned flat upfront will mea­sure 16 inches. Maria Lando, Mathmom

PS2: Puz­zle answer is below. Please try to solve it before check­ing out the answer 🙂

Maria Lan­do (aka The­Math­Mom) illu­mi­nates and demys­ti­fies math­e­mat­ics for adults, describ­ing its fun use in every­day life. The­Math­Mom has been fea­tured in mul­ti­ple media out­lets includ­ing The Boston Globe, The Jew­ish Advo­cate, and Red­book Mag­a­zine. Learn more at TheMathMom.com.

Puz­zle answer

Yes, math can come handy in the dress­ing room, so let’s refresh our geom­e­try! A shirt col­lar is almost cir­cu­lar, and as you remem­ber cir­cle cir­cum­fer­ence = 2 x Pi x Radius. Shirt size 16 means that a tape wrapped around your neck and two fin­gers posi­tioned flat upfront will mea­sure 16 inches.

At the time of your wed­ding: 2 x Pi x Radius of your neck = 16.

Now: 2 x Pi x new Radius of your neck = 2 x Pi x (wed­ding Radius of your neck + 1/4) = 2 x Pi x wed­ding Radius of your neck + 2 x Pi x 1/4 = 16 + Pi/2 = 16 + 3.14/2 = 17.57 (approx).

So, you are more around size 17.5 now.

Hap­py shopping!

 

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