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Welcome to the Student Academic Learning Services video on applied problems dealing with proportions.
In this video I'm just going to step through one word problem.
I'm going to show you all the steps that I take, and first deciphering the word problem
and then actually solving it.
So let's jump right in here.
A computer company found that 3 out of every 78 computers it sells are defective.
If the company sells 286 computers how many will be defective?
So the first thing I do with any word problem is you need to write down what you're given.
We're given that for every 78 computers, 3 are defective.
And we're looking to find, or we're asked to find, how many defective computers
there are going to be if we have 286 computers sold.
So we're looking for that value right there.
If you've watched our other proportion videos, it should be pretty clear how we're going
to solve this.
We're just going to set this up as a proportion and solve for the missing value.
So, we're going to title our solution here,
and we're going to assign a random variable.
So, let x be the number of defective computers.
So we're just assigning, this value here that we're looking for,
we're just going to assign it as x.
So let's just change colours here, and for every 78 there's
going to be 3 defective, and for 286 we're going to assign value x.
Now we're just going to cross, take the cross product of these.
So 78 times x equals 3 times 286.
78 times x is just 78x.
3 times 286 is 858, and now we're just going to solve for x.
So, divide both sides by 78, that disappears, so we're left with
x equals 858 divided by 78 is 11.
So for every 286 computers, we're going to have 11 defective.
Now when dealing with word problems it's usually in good form to have a closing statement.
So, therefore, for every 286 computers, 11 will be defective.
That concludes our video. If you have any questions regarding
what we did, the method I used to solve the word problem,
or any of the math involved in it, I encourage you to come to the SALS
centre located in room 204 of the Student Services Building
and make an appointment with the appropriate Learning Skills Advisor.
Thanks for watching.