General Word Problems Flashcards
Age Problems
- Define Variables for ages in present day
- Represent each age in future or past
- Set-up system of equations
- Solve for variable
Length Problems
- Assign a variable to each length (i.e. short, long)
- Set up an equation adding lengths to total lengths and another equation that relates the lengths to each other
- Solve for variable
Word Problems with 2 variables
You can substitute a variable into both sides of the equation to help you remove 1 variable and allow you to solve for the other variable.
Discounts
80% discount = Pay 20% of Price
$2,500 spent on tix with 80% = $2,500 x (5) = $12,500 worth of discounted tix
Fractional Parts of Whole Must Sum to the Whole
To avoid negative carry mistakes use Total = P1 + P2 + P3… that way if P2 = P1 - (4/5)P, you avoid forgetting to distribute the negative.
Compound Interest Formula
A = P (1+(r/n))^(nt)
A the is final value of principal plus interest
If the interest rate is giving as “y percent”, plug in (y/100) into r
Sometimes the question gives you only the interest earned, use A = P + I to solve for the variable needed.
Linear Growth
y = mx + b
Exponential Growth
Growth = Initial Value * Growth Factor^(growth periods) Decay = Initial Value * (1/decay factor)^(growth periods)
To determine the amount of growth, a growth driver must be know.
Ex:
The next number in the this sequence 2, 4, 6, 8… cannot be determined unless it’s given that the numbers are evenly spaced.
Sum of consecutive integers, consecutive even integers, and consecutive multiples of integers
sum of four consecutive integers is x + (x+1) + (x+2) + (x+3) + (x+4) = 4x+6
sum of 3 even consecutive integers is x + (x+2) + (x+4) = 3x+6
sum 3 consecutive multiples of 5 is x + (x+5) + (x+10) = 3x+15
Inequalities
As few as six = greater than or equal to six
at most five = less than or equal to five
at least = greater than or equal to
Objects in a line
If you are the the nth person from the beginning of the line and the mth person from the end of the line. Total number of people in line is equal to m+m-1
Common Mistakes/Understand the exactly what the question is asking for and the answers provided.
Understand exactly what the question is asking for. Look out for x old vs. x new. You might solve for x old but you need to find x new.
You might need to find the least number of something. Your math might give you x>integer, so the answer would be integer plus 1.
Take a second to understand the answer choices before rushing to select and answer.
Objects in the Line
Draw the line. Graph the positions for each scenario clearly and accurately. Be careful with the greater than/less than question. Slow down to confirm what the question is asking.