gmat word problems

• 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

• adding terms with the same units does not change the units
• the units of every term are the same

• treat units like numerators and denominators
• units that are multiplied together DO change

• 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

• a fraction whose numerator and denominator have different units but the same value
• e.g. 
• 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 x=1,800 mg

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)

• 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