Answer:
Step-by-step explanation:
Let's set this first one really carefully.
First of all, you were told by someone on the last sheet that you put one set of numbers with the same units on one side.
The other set of numbers goes on the other sided.
A proportion can never have more than 4 numbers, at least not at this level.
So let's start with the percents on one side
There's 80% and 100%. We'll put them on the left side.
80%
====
100%
Now we put an equal sign in.
80%
=== =
100%
Now you need the number of questions. One of the number of questions you don't know. Which one? It turns out that you don't know how many she got right. So let the number she got right = x
Now you have a choice. Which way do you write the proportion. Choice one is
x
==
20
or is it
20
===
x
?
The answer is the total number of questions (20) goes straight across from 100. 100% of the questions is equal to 20.
So the proportion is
80 x
== = ====
100 20
Now I wonder if you know what to do from here? This is a question you will have to answer for me. But the next step is to cross multiply.
Rule: Upper Left * Lower Right = lower left * Upper Right.
Always true. Always done for every question.
80 * 20 = 100 * x Multiply out the left
1600 = 100 * x Divide by 100
1600/100 = x Do the division
16 = x
In other words. There were 16 questions she got right.
Two
You have a wonderful guide for teaching this. This question is of paramount importance.
The percents are known. 90% and 100%. Same as above.
So the left side of the proportion is known.
90
==
100
We again, just as in the last question have to find a number. A crew contains 30 people. That's 90% or 100%, which? Think carefully before reading on.
If you thought it was 90%, you would be incorrect. 30 people represents everyone. So the second side is
x
==
30
or
30
==
x
Again the 30 goes opposite the 100
So x must be what 90% represents in number of people
The proportion is
90 x
=== = ===
100 30
We are not looking for a %. We have both of them. We aren't looking for the whole. We know that's 30
Answer: So must be looking for a partial.
Three
You know what the whole is (or should). It is the starting price of the handbag which is 72 dollars.
You know what 100% of the handbag is (72 dollars)
You know what the "part" of the whole is 21.60
So you must be looking for the % which is the unknown.
x 21.60
== = ===
100 72.
Four
I'd like to leave 4. PM me about a possible answer.
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