David W. answered • 05/28/15
Tutor
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(90)
retired
Word (story) problems are easy if you use a table to translate the words to precise, concise math variables and operations. For example,
Is means =
Larger than +
Four times a 4*a
F is 550 less than S F = S – 550
Total of A, B, C A + B + C
This seems obvious – until you get stuck on a word problem. So,
“the first company” , “a second company” becomes Let their costs be F and S
Let K be the number of kilograms
“$20 to ship a medium box, plus an additional $2 per kilogram” F = $20 + 2*K
“10 for the same size of box, plus an additional $3 per kilogram” S = $10 + 3*K
“the two shipping methods will cost the same amount” F = S
“What is that weight?” report K
Is means =
Larger than +
Four times a 4*a
F is 550 less than S F = S – 550
Total of A, B, C A + B + C
This seems obvious – until you get stuck on a word problem. So,
“the first company” , “a second company” becomes Let their costs be F and S
Let K be the number of kilograms
“$20 to ship a medium box, plus an additional $2 per kilogram” F = $20 + 2*K
“10 for the same size of box, plus an additional $3 per kilogram” S = $10 + 3*K
“the two shipping methods will cost the same amount” F = S
“What is that weight?” report K
Now, the math:
F = S
20 + 2K = 10 + 3K
$10 = K
Checking:
Is $20 + 2($10) = $10 + 3($10) ?
$40 = $40 YES
F = S
20 + 2K = 10 + 3K
$10 = K
Checking:
Is $20 + 2($10) = $10 + 3($10) ?
$40 = $40 YES
David W.
Cool ! (This will help you understand what they call the "break even" point).
You have two equations: (1) the cost F for the first shop for various weights, and
(2) the cost S for the second shop for various weights
At K = 10 kg (note: I made an error; K is not $ it is kg.) the lines cross. That point is on both lines. It's the point where the prices are equal.
So, let x be the weight in kg, and have two lines plotted for y, which is the cost to ship a package of that weight.
(THX for being patient with my errors and typos; I edit my responses way too much.)
Report
05/28/15
Em P.
05/28/15