Can anyone give me an example of using algebra in everyday life?
Easy. I’m moving next week and have rented a truck to haul my stuff. In addition to the daily rental fee for the vehicle, there’s also a fee for the distance I drive the thing: $0.40 time x miles. You should recognize that as an algebraic equation.
Cabinetmaking.
I am a cabinet maker, and doing layouts for cabinets is one practical application.
Algebra strengthens abstract reasoning skills. It also helps solve seemingly complex word problems by allowing the use of variables & an equation.
OK so you asked for an example. See this thread:
http://boards.straightdope.com/sdmb/showthread.php?threadid=115311
Also, depending on what you do for a living, or what you some day wish to be doing, there is quite a lot of useful algebra in everyday life.
Algebra is used throughout life. I can’t think of many jobs where you don’t use it. Most people may not think of it as ‘algebra’ without writing down a formal equation, but it still is.
Computer programmers deal with algebra every day. The coolest programs like games require the most knowledge of Algebra.
I used calculus last year to calculate how many paving stones I’d need for my irregularly-shaped patio. Using calculus, I had a precise answer in about five minutes. Without it, I would have purchased too few or too many bricks.
As a pilot, I use algebra all the time. Pilots have to learn so many formulas that one of the standard tools is a circular slide rule, and every pilot has to use it.
Just a couple days ago, a friend and I had lunch at a restaurant. Since we were each paying for our own meal, I needed to know how to split the tax. I couldn’t remember what the state sales tax was (it had increased relatively recently), but I know that the subtotal for the meal was $12.77, and that the tax on that was $0.99. The tax rate was therefore x, where x satisfied $12.77 * x = $0.99. Solving for x was an everyday application of algebra.
One word - Computer Programming.
shit! that’s two.
In fact, you’d be surprised at just how many instances there are in which algebra is useful.
Possibly an easy way to understand why algebra is useful in general is if you think of it as a machine, the machine stays the same, but you can pass any number you like into the machine and it produces a useful number at the other end.
like fsk / (ms*8) = nsd
fsk = file size in kilobytes, ms = modem speed, nsd = number of seconds for download. (the equation is probably wrong but that’s irrelevant in this context).
the usefulness of algebra in that instance is that you can give it any file size you want and it will correctly work out the number of seconds you have to wait for it to download.
I like to cut envelopes out of sheets of paper to send hand-made greeting cards. In order to do this, you cut a rhombus out of a sheet of paper and then fold it in four places, making your classic envelope look. I want to mail things as large as possible, so I took the time to determine the largest rhombus which can be cut out of a non-square rectangular sheet of paper with given dimensions. Algebra!
I used to work at a small zoo, owned by a guy named Al, and I dealt with Al’s zebra all the time.
::: ducking :::
I’ll give a real life example. A friend of mine built a summer home. He bought a property by a lake, rented a chain saw and cut down a bunch of trees, stripped and debarked them, dried them and built a trough to impregnate them with preservative, hired someone to level the ground and pour a concrete slab and then hired a pair of construction locals to actually build it. He worked along with them. When they needed a log (this was, BTW, literally a log cabin) of a certain length, he found a suitable one and dragged it over. They came to doing the roof. The span was 24’ and the peak was 5’ high, which meant that the logs had to span the hypotenuse of a triangle whose legs were 5’ and 12’. When he informed them that a 14’ log (there was to be a 1’ overhang) would fit exactly, they were absolutely incredulous. How could he know that. They didn’t believe him until he brought them a 14’ log and it fit. Their habit would have been to estimate that, say, a 16’ foot log would be long enough and then cut it down to what they needed. They considered what he did to be a kind of magic, which is a good illustration of Clarke’s law (I think it was Arthur C. Clarke) that any sufficiently advanced technology is indistinguishable from magic.
But I think the question behind the question was why do we insist that everyone study algebra in HS and I think the only answer is to give people a feel for the quantitative. Maybe we should instead teach elementary statistics. Most of the statistics and especially the graphs in the daily papers are worse than worthless, since they are misleading. For example, I just read somewhere that the likely loss of life from a “dirty bomb” would be one, in addition to the number killed in the explosion, but the real cost (in money and, quite possibly, in life) would be from the panic and the fleeing and looting that would occur. Even if that is a best case estimate (which it did appear to be), the point is well-taken. We flee from minor risks and unthinkingly accept major ones. Forty thousand people die in the US each year from auto accidents and a couple hundred thousand from smoking, but we have changed our way of life in response to terrorism that has killed fewer than 3000.
I knit.
Last night I started in on a new pattern. In the set of instructions, they tell me how many rows and stitches I should get for every 4 inches. They also tell me to do certain things a certain number of inches in. To make the sweater look ok, I need to convert that to # of rows (measuring never works anywhere near as well.)
In this particular case, the pattern (as written) is also too small for me and even if it was big enough, the arms would be too short. So, I have to adjust the instructions to make it proportionally bigger, and then again to make the sleeves proportionally longer. Admittedly, I could guess randomly and just add a few stitches here and there, but I get a much better result if I actually do a calculation. And this is an easy, simple sweater - anything complicated takes much more time.
i have a friend living in japan who told me he’s making about 216,000 yen a month, which he told me is approximately $2080. he also said he had found an apartment for 80,000 yen but neglected to tell me how much that is in dollars. so, by setting this up…
216000/2080=80000/x
…and solving for x, i was able to get an idea for how much his apt is costing him.
Back when I was a horribly underpaid laboratory technician I shared a four bedroom apartment with three other guys. The four bedrooms varied in terms of size and quality, so we all agreed it would be unfair to just divide the total apartment rent by four; the people with the bigger nicer bedrooms should pay more than the people with the smaller crummier bedrooms. We decided that whoever had bedroom A (the nicest) should pay 20 dollars more than 1/4 the total rent, and that the two guys in rooms C and D should get an equal discount. My roomates were suprised that I was able to quickly come up with the amount those two guys should pay…10 dollars less than 1/4 the total: if one guy pays 20 dollars more, than two paying 10 dollars less evens everything out. Algebra.
I’ll not bother to add yet another example, although they abound in my life.
Algebra is basically symbolic logic. And that remains difficult for many. I have known two people whose endeavors to graduate from college were thwarted by Texas’ state schools requirement that they pass algebra. Both were otherwise 3+ GPA students, and for one of them that algebra course was all that remained! She just could not get it. sigh