Better Students Ask More Questions.
1)tickets decreased from $90.00 to $85.002)a $170.00 bicycle decreased to $155.00there...
3 Answers | add yours
High School Teacher
Both of these are simple percentage problems. Your percentage formula is, as always:
where the part of the whole is equal to the percentage over 100.
So in this case, your part for number 1 is $5 (the amount decreased) and your whole is $90. Your percentage is unknown, so let's call that X. So your re-written formula should be:
$5/$90 = X/100
This is a proportion, so we can cross-multiply, so:
$5 x 100 = 500
$90 x X = 90X
So now we have 90X = 500.
In order to isolate X, we need to divide 90 from both sides.
90X / 90 = X
500 / 90 = 5.56
So, X = 5.56, and therefore the price decreased by 5.56%.
For number 2, your part is $15, your whole is $170, and again your percentage is unknown, X.
$15/$170 = X/100
So again, we cross-multiply, and get:
$15 x 100 = 1500
$170 x X = 170X
1500 = 170X
Now we isolate X by dividing out the coefficient from both sides.
170X / 170 = X
1500 / 170 = 8.82
Therefore, X = 8.82%, your percentage of decrease.
Posted by adrigon on October 22, 2008 at 6:27 PM (Answer #1)
Middle School Teacher
This might be an easier way to think about it.
In the first problem, the amount of decrease is $5. What you need to find is what percent $5 is of $90 (since $90 is the number you started with).
Percent problems can always be solved using:
Part / Whole = %
Just plug in what you know and solve it to find the missing piece. Here, you know the part ($5) and the whole ($90).
So, the % = $5 / $90 = .0555555 etc
Remember that .05 is the same as 5%. So, just round the answer to however many places your teacher wants.
.0555555 etc = .0556 (5.56%) or .056 (5.6%) or .06 (6%) depending on how exact you need to be.
Posted by cburr on October 26, 2008 at 11:00 AM (Answer #2)
1) The tickets decreashed from 90 dollars to 85 dollars, so the price change is 5 dollars.
Percentage decrease= decrease/ original amount * 100% so:
% decrease= 5/90 * 100%= 5.55%
2) The price change is 170-155= 15 dollars
% decrease= 15/170*100%= 8.82%
Posted by revolution on July 4, 2010 at 5:47 PM (Answer #3)
Join to answer this question
Join a community of thousands of dedicated teachers and students.