Sunday, June 24, 2007

Math Problem

I hated math until I finished high school and no longer had to do it on a regular basis. When I do math now, it is on my own terms, no teacher is looking over my shoulder and making me feel self-conscious. I was never *that* bad at math, but I was generally pretty slow about it. Now that I'm not timed anymore, it doesn't even matter. So these days math and I get along pretty well.

This is especially good when it comes to knitting, as we often deal with math. I do all sorts of division and multiplication these days. This weekend I ran into a particularly cool math problem, and I thought I'd share it with you.


A knitter wants to make the Cap Shawl from Victorian Lace Today. This shawl calls for 1700 yds of yarn to make a shawl 74" across (radius: 37"). The knitter finds a skein of Merino Oro laceweight with just 1375 yards. How big a shawl can she make?

To solve: the first step is to figure out the area of the pattern shawl, so we know how far 1700 yards gets us. (we are rounding for sanity's sake)

A=πr^2
r=37
A=π * 37^2
A=π * 1367
A=4300 in^2

Ok, so 1700 yards makes 4300 square inches of lace. Now we need to find out how many square inches of lace (x) we can make with 1375 yards of yarn. My algebra here gets kind of ugly, but bear with me.

(4300 in^2)/(1700yds)= x/(1375 yds)

Remember your algebra steps! Multiply across...

1700x = 4300 * 1375
1700x = 5,912,500
x = 5,912,500/1700
x = 3478 in^2

So the new shawl will have an area of 3478 square inches. What's the radius of our new shawl?

A = πr^2
3478 = πr^2
r^2 = 3478/π
r^2 = 1108
(Not even gonna attempt the square root sign)
r = 33 in

So the new shawl will be 66" across, which I think is perfectly acceptable, as I am 66" tall.

Once I've made a swatch of the pattern I'll figure out how many rows I need to leave off in order to reduce the radius by 4". I'll edit the lace pattern from there (more math!)

So, wasn't that fun? Here's something even more fun, for those of you who've made it this far: this yarn ($16.50) was my first wedding-related purchase. 3478 square inches of knitting from now, I'll have my veil done!

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12 Comments:

At 6/24/2007 7:30 PM , Blogger Heather said...

I got the beginning of the post and the ending, but you lost me in the middle. I will, of course, come crying to you when I need some math help.

The veil will be beautiful!

 
At 6/24/2007 10:53 PM , Blogger sherriknits said...

Oh my, you lost me! Of course, today I was the mother of the bride so maybe that counts! Tell your mom to look forward to your day with all her heart, there is nothing like watching your little girl have the day she always dreamed of (and you too!)

 
At 6/25/2007 2:23 AM , Blogger Nell said...

Are you mad! That made my head hurt!!

:)

 
At 6/25/2007 7:12 AM , Blogger Da Gu Ma said...

Wow! I'm so proud! And to think people in our city think the high school you went to isn't very good...

You will be a beautiful bride in that gorgeous veil!

 
At 6/25/2007 9:30 AM , Blogger AuntieAnn said...

Wow, good job! I didn't try to follow all of your steps, but good for you for working that through! That will be one gorgeous veil.

 
At 6/25/2007 1:15 PM , Blogger WineGrrl said...

That is going to be lovely, even though the formulas made my head hurt! ;-D

 
At 6/25/2007 8:35 PM , Anonymous kelp! said...

You're knitting your veil? What a super trooper. Get it done in plenty of time, I had a wedding shawl blocking two days before the wedding, and that was No Fun.

 
At 7/05/2007 8:56 PM , Blogger knitty_kat said...

yer knitting yer veil? Oh, how nice!! That's an awesome idea and I bet it will be spectacular!

 
At 7/10/2007 2:35 PM , Blogger LilKnitter said...

What a fabulous veil that will be! Such a neat idea...

 
At 7/10/2007 4:08 PM , Anonymous Maia said...

Math! How I love thee! I love seeing math in action.

It looks beautiful so far.

 
At 2/25/2014 10:56 PM , Blogger I3litzI2 said...

37^2 = 1369

 
At 7/22/2016 11:39 AM , Blogger Meira Shana said...

I failed 9B algebra, in spite of the teacher's constant help.

So, I had to take that class again which meant that 9A Algebra had to be done in Summer School (which my mother could not afford!)

The gal sitting next to me was blind enough to have to do the lessons with a Braille little thingy - and I gave her the information that the teacher had on the chalkboard.

That was an interesting summer: that was the first and last time I saw my father in years; and I passed Algebra with a D and my fellow student passed with an A.

Sheez! She should have been helping me! LOL

A few years ago, my daughter, who is a teacher of 5th graders, told me that she could teach me an easier way to do Algebra. I thanked her and told her that in all the years since 9th grade I have never had to use that technique.

Then I see what you wrote about knitting that gorgeous shawl.

Well, pooh! I'm still not understanding and I'm not going to summer school again.

Gorgeous knitting!! Thank you for sharing your beauties and I hope you are smiling at my story.

 

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