MGMAT Flashcards
What is the Algebraic Translation strategy
- Assign variables.
- make up letters to represent unknown quantities to set up equations.
- choose meaningful letters, avoid subscripts
- try to minimize the number of variables - Write equations.
- translate verbal relationships into math symbols.
- book 4, pg. 14 - Solve the equations.
- Answer the right question.
4 Tips for Translating Words Correctly
Avoid writing relationships backwards.
Quickly check your translations with easy numbers.
Write an unknown percent as a variable divided by 100.
Translate bulk discounts and similar relationships carefully.
When should you use charts to organize variables
Make a chart when several quantities and multiple relationships.
Ex: age problems - people in rows, times in columns
How to use charts to organize variables
- Assign variables.
- try to use 1 variable for simplicity. - Write equations.
- use leftover information/relationships to write equations. - Solve the equations.
- Answer the right questions.
In a typical Price_quality problem, what are the 2 relatiionships
1) the quantities sum to a total AND 2) the monetary values sum to a total.
How to go about solving Prices & Quantities problems
Be able to write word problems with two different types of equations:
- relate the quantities or numbers of different goods.
- relate the total values of the goods.
- Assign variables.
- try to use as few variables as possible. - Write equations.
- for every X number of variables assigned, write X-1 equations.
- columns in a table = price, qty, total value
- rows = types of items, total
When a variable indicates how many objects there are, it must be WHAT kind of number
MUST be a WHOLE number
You can solve a data sufficiency question with little information if
whole numbers are involved.
You can use a table to generate, organize, and eliminate information when there are WHAT numbers.
WHOLE numbers.
POSITIVE CONSTRAINTS =
POSSIBLE ALGEBRA
Rates & Work Problems are marked by what 3 primary components
rate, time & distance or work.
Rate x Time =
Distance (RT=D)
Rate x Time=
Work (RT = W)
Five main forms of rate problems:
- Basic motion problems
- Average rate problems
- Simultaneous motion problems
- Work problems
- Population problems
Basic motion problems involve
rate, time and distance.
D = R T
Rate = ratio of distance and time Time = a unit of time Distance = a unit of distance
Difficult problems involve rates, times and distances for
more than one trip or traveler.
Solve multiple RTD problems by…
- expanding the RTD chart by adding rows for each trip.
Typical rate (speed) relations:
- twice/half/n times as fast as
- slower/faster
- relative rates
Typical time relations:
- slower/faster
- left… and met/arrived a
Sample Multiple RTD Problems
The numbers in the same row of an RTD table will always multiply across. The specifics of the problem determine which columns will add up into a total row.
R x T = D
- The kiss (or crash) ADD SAME ADD
- the quarrel (away from) ADD SAME ADD
- The chase. SUBT SAME SUBT
- the round trip VARIES ADD ADD
- following footsteps VAR VAR SAME
- second-guessing (same person) VAR VAR SAME
When using variables, use them for R or T to make math easier.
If something moves the same distance twice but at different rates, then the average rate will ALWAYS-SOMETIMES-OR NEVER be the average of the two given rates.
NEVER
On Average RTD Problems,
Find the total combined time and the total combined distance. Find the average rate from these totals.
Basic Work Problems
Involve time, rate and work.
In basic work problems, Work stands for
work: number of jobs completed or items produced
In basic work problems, TIME stands for
- time: time spent working
In basic work problems, RATE stands for
- rate: ratio of work to time, amount completed in one time unit
Always express as jobs per unit of time, not as
time per job.
how to Determine the combined rate of all the workers working together
sum the individual working rates.
What do If one agent is undoing the work of another,
subtract their working rates
If a work problem involves time relations, then the calculations are just like
distance problems.
What happens in Population problems
Some population that typically increases by a common factor every time period.
What to do with a population problem
Use a population chart:
Make a table with a few rows with NOW in the middle row. Work forwards and backwards from NOW using the problem’s information.
what number should you pick for the starting point in a populaton problem
Maybe pick a smart number for the starting point - choose a number that makes the math simple.
A ratio expresses WHAT
Express a relationship between two or more quantities.
A relationship a RATIO expresses
division
RATIOs Can be expressed with the word “to”, using a WHAT, or by writing a WHAT
using a colon, or by writing a fraction.
Ratios can express a ___-_____ relationship or ___-____
part-part relationship or part-whole.
Can you find the quantity of each item from a ratio
Cannot find the quantity of each item from a ratio, but if 2 quantities have a constant ratio they are in direct proportion to each other.
Simple ratio problems can be solved with
a proportion.
How to solve a simple ratio problem with a proportion
a proportion.
Cancel Tips
Cancel factors out before multiplying to save time. Can cancel either vertically within a fraction or horizontally across the equals sign.
Unknown Multiplier Technique
Represent ratios with some unknown number/variable to reduce the number of variables and make the algebra easier.
How often can you use the Unknown Multiplier Technique
You can only use it once per problem. You should use it when neither quantity in the ratio is already equal to a number or variable.
How to combibe ratios with common elements
multiply all of the ratios by the same number (a common multiple).
In Multipls Ratios, what should you make the term you are working with
the least common multiple of the current values.
in COMBINATORICS, what are you countng
Counting the number of possibilities/ways you can arrange things.
Fundamental Counting Principle:
if you must make a number of separate decisions, then MULTIPLY the numbers of ways to make each individual decision to find the number of ways to make all the decisions.
When use the Slot Method
for problems where certain choices are restricted