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My son's walks around mimicking his typing teacher, who say's "Yous stop banging on them keys!)
I don't claim to be an expert, but I disagree. I say it is 2.
48/2(9+3)
48/2n, when n=9+3
n=12
2n=24
48/24
2
I know this because I corrected my son's homework just last month, and I was greeted the next day with an angry stare and some big red X's on his homework on only the ones that I "helped" with, lol. I emailed the teacher to explain, and this was what he explained.
While order of operations dictates that division and multiplication be done from left to right, variables are an exception. 8 / 4n when n=2 equals 1, not 4
4(2) is another way of writing 4n, it is still considered a variable.
Plain old wrong.
Order of operations does not change if there is a variable unless there are parentheses. Variables are not a special case and are not treated any differently than the numbers they stand for.
8/4n = 2n because it is really 8/4*n. Writing a number next to a variable is the EXACT SAME THING as putting a multiplication sign between them. No more, no less.
so if 5 friend choose to split a rental car we need for 4 days. We don't know how much the rental car is yet.
so 5 / 4(the cost of the daily charge) is how much each of us will pay. 5 / 4n
So if the car cost $20 a day, and the bill comes to $80
my mathematician, engineer, PhD, and algebra teacher friends and I will pay $16 each for a total of $80
you and your google, excel, metlab, and fifth grade student friends will pay $25 each for a total of $125
again, I would much rather be on the side of the PhDs, mathematicians, and engineers.
LOL. Oh the internet.
You REALLY should not be correcting your son's math worksheets. The very first rule of order of operations is parentheses. Your "example" above is a good reason to understand where to put them.
Your equation is set up wrong and you didn't even do the math right using your bizarre logic. If n=$20, 5/4n would be 5/80 which means you would pay 0.0625.
The correct equation for cost per person is x = total *4/5 and since you have issues with operations we can make it simpler. X = (total*4)/5 they mean the exact same things.
Oh and this is a scientist with a graduate degree telling you this.
This thread is funny. My daughter's K teacher was from Granite Falls, GA. In case you were wondering, they have a pretty horrendous dialect in "those there" parts, and she was no exception. She was undoubtedly one of the best teacher's my children have been fortunate enough to have. My daughter did pick up her colloquialisms, and over the summer said colloquialisms disappeared.
This thread is funny. My daughter's K teacher was from Granite Falls, GA. In case you were wondering, they have a pretty horrendous dialect in "those there" parts, and she was no exception. She was undoubtedly one of the best teacher's my children have been fortunate enough to have. My daughter did pick up her colloquialisms, and over the summer said colloquialisms disappeared.
Clearly you should have been banging down the door of the principal demanding she be fired.
so if 5 friend choose to split a rental car we need for 4 days. We don't know how much the rental car is yet.
so 5 / 4(the cost of the daily charge) is how much each of us will pay. 5 / 4n
So if the car cost $20 a day, and the bill comes to $80
my mathematician, engineer, PhD, and algebra teacher friends and I will pay $16 each for a total of $80
you and your google, excel, metlab, and fifth grade student friends will pay $25 each for a total of $125
again, I would much rather be on the side of the PhDs, mathematicians, and engineers.
The question is "How many dollars per person should be paid?". That's what we're trying to find out.
It is incorrect to model this problem with 5/4n which would provide you with units of people per dollar. The answer should be in units of dollars per person. The denominator and numerator need to be switched.
It would 80 dollars divided by by 5 people. The math would be (4 days * ($20/day))/5 = $80/5 = $16/person.
48/2(9+3)
48/2n, when n=9+3
n=12
48/2*12 = 24*12 = 288
Once the parenthesis, exponents, addition, and subtraction have been completed and all that remains is multiplication and division, the order of operations dictates from left to right.
Plug it into excel, matlab, or google and you'll see 288.
I wonder how many teachers actually get this wrong. I wonder how many engineers get this wrong and make incorrect assumptions which results in a wing falling off an airplane. I've asked dozens of engineers and PhDs and mathematicians and they all wrongly say 2. Ask a fifth grader or fifth grade teacher and they'll get it right and tell you 288.
Yes.
The problem is that as written, the problem *looks* ambiguous to the average person.
A mathematician would write it as (48/2)(9+3) = 288
and 48/(2(9+3)) = 2
If you enter the first problem exactly as written in the original problem into a scientific calculator, you get 288. If you enter it into an old-fashioned non-scientific calculator, it will give you 2.
The problem is that as written, the problem *looks* ambiguous to the average person.
A mathematician would write it as (48/2)(9+3) = 288
and 48/(2(9+3)) = 2
If you enter the first problem exactly as written in the original problem into a scientific calculator, you get 288. If you enter it into an old-fashioned non-scientific calculator, it will give you 2.
This is exactly why I came up with the answer of 2. Because I would not have written the problem that way in the first place. As the original is written, I would have interpreted it the way you have it in the second example:
48/(2(9+3))
Which does, in fact, equal 2.
That might not be how it was intended, but that would've been how I interpreted it.
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