gmat word problems

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  1. four steps
    • 1. id what value the question is asking for (desired value)
    • 2. id unknown values and label them with variables
    • 3. id relationships and translate them into equations
    • 4. use the equation to solve for the desired value
  2. additive relationships - subj. algebraic translation
    • adding terms with the same units does not change the units
    • the units of every term are the same
  3. multiplicative relationships - subj. algebraic translation
    • treat units like numerators and denominators
    • units that are multiplied together DO change
  4. common relationships - subj. algebraic translation
    • total cost ($) = unit price ($/unit) x quantity purchased (units)
    • profit ($) = revenue ($) - cost ($)
    • total earnings ($) = wage rate ($/hour) x hours worked (hours)
    • miles = miles per hour x hours
    • miles = miles per gallons x gallons
  5. conversion facor
    • a fraction whose numerator and denominator have different units but the same value
    • e.g. Image Upload 1
    • ex. a certain medicine requires 4 doses per day.  if each dose is 150 mg,how many mg of medicine will a person have taken after the end of the third day, if the medicine is used as directed?
    • 3 days x Image Upload 2xImage Upload 3=1,800 mg
  6. Integer Constraints
    ex. If Kelly received 1/3 more votes than Mike in a student election, which of the following could have been the total number of votes cast for the two candidates? (54, 55, 56, 57, 58)
    If Kelly received 1/3 more votes than Mike, she received 4/3 the number of votes.  So what times 4/3 will equal an integer? only multiple of 3 will cancel out the 3 in the denominator. the number of votes Mike received is a multiple of 3, then the number of votes Kelly received must be a multiple of 4.  Taken together, the total number of votes cast must then be a multiple of 7.  (answer is 56)
  7. Hidden Constraint
    DS ex. A store sells erasers for $0.23 each and pencils for $0.11 each.  How many erasers and pencils did Jessica buy from the store?
    (1) Jessica bought 5 erasers
    (2) Jessica spent $1.70 on erasers and pencils
    • Statement 1 by itself is not sufficient
    • On the surface, statement 2 should not be enough.
    • If J bought 1 eraser, 170 - 23 = 147 cents on pencils (but 147 isn't divisible by 11)
    • ... If J bought 5 erasers and 5 pencils: 5(23) + 5(11) = 170
    • thus, statement 2 is sufficient by itself
Card Set
gmat word problems
word problems on the gmat
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