Percents Flashcards
How should you handle percents that contain a fraction?
Divide the fraction by a 100 and simplify the resulting fraction
What does percent mean?
Per one hundred
Out of 100
How do you express a percent as a decimal?
Shift the decimal point two spaces to the left
How do you convert a decimal into a percent?
Shift the decimal two spaces to the right
How do you convert a fraction into a percent ?
Multiply it by 100 (break the numbers down into similar terms)
You may need want to convert it into a decimal first
How should you take a percent of a number?
Convert the percent into a fraction and translate the word “of” as “multiply”
How do you get 10% of a number?
Shift its decimal spot one space to the left
How do you get 1% of a number?
Shift its decimal point two spots to the left
How do you calculate a percent change?
Difference / original = percent change
Whats the equation for when an object increases or decreases by a certain percent?
Original * ( 1 + or - change) = new
How should you handle consecutive percents?
One step at a time, dont combine the changes
Whats the formula for simple interest?
Simple interest = principal * rate * time
I= prt
Describe compound interest
Compound interest is added back to the original principal so that both the principal and the accrued interest garner interest
What is the compound interest formula?
Total value = P (1+R/T) ^TY
What should you remember when working with compound interest?
Compound interest always generates more interest than simple interest
The more frequent the compounding the more interest there will be
What should you do if a percent problem does not include a specified amount ?
Let the original value equal 100
How do you solve what percent of a is b questions?
(Is b / percent of A) * 100
If your percent change is a variable what should you do ?
Express the percent change as a fraction
Whats the difference between a mixture and alteration problem?
Mixture problems combine two separate mixtures
Alteration problems alter change or redistribute just one mixture
What ingredients matter in a mixture problem?
The ingredient they have in common to the individual mixtures and the final mixture.
How do you solve mixture PUQS
Let the total quantity of one of the mixtures equal 100, and let the total quantity of the other mixture equal x
What is the RAFs short cut for mixture PUQs problems?
1) determine the range between the percentages of the individual mixture or solutions
2) then get the absolute differences between the individual percentages and the percentage of the combined mixture
3) finally express each difference as a fraction of the range
4) the bigger fraction refers to the individual mixture or solution whose percentage is closer to the percentage of the combined mixture
How do you calculate a percent increase / decrease between two numbers ?
I.e. if the price of an item increases from $24 to $30, what is the percent increase in price ?
Find the difference between the values and put that amount over the original number
I.e. 30-24 =6
The original value was $24
So the answer is 6/24 = 1/4=.25
