Posted on 03/10/2015 5:48:37 PM PDT by MNDude
That’s fine, but it’s an assumption not justified in the statement of the problem.
Can you do some of that calculus and tell me an L and W that multiply to 12 and a 2L+2W that add to one of the other choices? I’m just looking for one set of numbers and will concede.
5.19*2.31=11.9889 not 12.
8.6*1.39=11.954 not 12. They said the area was 12.
Yep.
It’s my assumption and I’m sticking to it!
What are the appropriate significant digits for a baby blanket within the context of this problem, as stated and making no assumptions?
I believe it may be 2, because of the area value of 12, but I've never liked the constraints on pure mathematics enforced in engineering disciplines.
Oh no. Not significant digits! Yuck. I suppose since the area is specified with 0 decimal places, we should assume no rounding right? :)
8.60555127546 x 1.39444872454
-- or --
Solve the equation I gave you to as many significant digits as you want.
But be advised of this very simple fact: There is no measurement you can do with a ruler that has more than three significant digits, no matter how exact it looks. That includes something that appears to be "exactly" 3 inches by "exactly" 4 inches.
The truth is most actual measurements are irrationals, and the number of measurements that are integral (or even rational) is a set with probability measure ZERO.
= ~X
My son the engineer and I have almost come to blows over this issue.
For a problem involving 2 significant digits, he would restate a length of 12,247 units as 12,000, and he would restate a length of one unit as 1.0.
I view this approach as indefensible in practical problem solving in matters such as baby blankets.
The minimum perimeter is obtained with a circle, diameter approx 3.9 units, perimeter approx 12.28 units.
This issue alone could generate a spin-off thread.
I hope it won't, but it could.
That still doesn’t multiply to 12. They didn’t say they measured it. They simply said it was 12 square units. I’m not sure how we can get ripped for assuming a rectangle while calc majors get away with assuming a GIVEN area of 12 is something other than 12.
Aren’t boarders discriminatory?
Here is a great example I used to give engineering students who insisted on copying down 14 significant digit answers (directly from their calculators) about why significant digits keep you from looking stupid.
A docent shows a class of kindergartners a T-Rex skeleton. Little Johnny asks "Mister, how old is this skeleton?"
The docent replies: "This skeleton is 65 million and 20 years plus 14 days and 3 hours old."
"Wow!" says the kid, "How do they date it so accurately?"
The docent replies: "Because I just had my 20th anniversary two weeks ago on Monday, and we are a hour away from lunch, and on the day I was hired they told me that this skeleton was 65 million years old!"
Here's another example: The liars at NASA claim that 2014 was "the warmest year on record." But 2014 is "warmer" than the "next warmest year" by a difference of 0.02°, while the error in temperature measurements is 0.5°. That means, in fact, that 2014 isn't warmer at all. To the significance known, every year since 1997 is exactly the same temperature. Their differences are purely nominal. In fact, within the range of significance, 2014 could actually be one of COLDEST years since 2000.
Of course, but unlike many of the assumptions made by others on this thread, the assumption of a rectangular blanket is reasonable.
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