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37 Cards in this Set
- Front
- Back
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How is average Rate calculated?
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It is the total distance divided by the total time and not the average of the two rates. It will be closer to the smaller rate
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What is the formula for rate of work when the number of jobs are known?
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Number of jobs divided by time taken to complete the jobs
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What is the formula for rate of work when the time taken to complete one job is known?
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1/Time taken to complete 1 job
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What to do with rate when two or more agents are doing the same job?
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Add their rates to get combined rates
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What is productivity ratio?
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Rate of doing work.
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What is the fundamental counting principal?
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The number of ways to make separate decisions is by multiplying the way to make each individual decisions. e.g. the number of different types of sandwiches thats can be made with 2 types of spread and 3 types of bread are 3*2=6.
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What about problems involving choices that are restricted or affect other choices? e.g. James and Jill will sit only with each other etc.
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For problems where certain choices are restricted or affect other choices, first start with the restricted choices
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4!
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24
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5!
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120
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6!
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720
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7!
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5040
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8!
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40320
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9!
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362880
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10!
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3628800
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What are the number of ways of putting n distinct objects in order, if there are no restrictions?
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n!. This is similar to the fundamental counting principal where after ordering 1 object, there are only n-1 ways of ordering the remaining objects and so on.
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What is an anagram?
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It is a rearrangement of the letters in a word.
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How do you calculate the number of anagrams a word can make?
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It is the factorial of the number of letters divided by the factorial of the number of times each individual letter is repeated. e,g, ATLANTA = 7!/3!2!
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What technique to use to solve most rearrange type questions?
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Annagramming
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What technique to use to solve combination type questions?
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Anagram matrix.
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If 7 people have only 3 seats, what are the different combination of arrangements possible?
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There are 3 unique seats and 4 remaining so 7!/4!
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If only 3 among 7 people are selected for a flight, then how many combinations are possible?
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Only one flight seat is available for 3 ppl to fill and rest 4 are remaining so 7!/3!4!
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How to solve questions that require picking from 2 or more different pools?
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Anagram each pool and multiply the results together. The trick is to identify that there are different pools.
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What type of arrangement questions are the most complex and how to tackle them?
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Arrangements that have constraints are the most complex. Take for example, A through E went for a movie but A and E will not sit with each other. Find combinations?First, find the total no of combinations without any restrictions = 5!. The find the no of ways everyone can sit together considering A&E as one = 4!. Next find out how many ways A&E can sit=2 and then combine that with the number of ways assuming they are one because they can interchange=2*4!. Finally subtract this with original = 5!-2*4!.
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What method to use if you encounter a problem with restrictions?
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Use slot method since anagram method wont work with restrictions
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What is the formula for permutation?
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?
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What is the formula for combination?
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?
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What are you supposed to guess when it is written - "Cost per employee" or "shared evenly" ?
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They are talking about averages.
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What are weighted averages?
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?
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What should all weights in a weighted average problem add up to?
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They should add up to 1.
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What is the formula for finding weighted average?
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weight(term)/sum of weights+weight(term1)/sum of weights...
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the weighted average of 2 terms will be closer to which of the two terms?
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It will be closer to the term with the heavier weight.
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If you know the ratio of the weights, you can get the weighted average.
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Si
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How to identify what unit to use for the weight?
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Pick the unit of the denominator. e.g. to find average speed, pick time as the weights unit.
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How to solve question on overlapping sets that have only two categorizations?
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Use the double set matrix and the columns should be mutually exclusive.
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How to solve question on overlapping sets that have percents or fractions?
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Use smart numbers - for fractions use the total as a common multiple of the denominators
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How to solve question on overlapping sets that have only three categorizations?
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Venn diagrams
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What to find out when given, "How many different students are there in at least one of 3 clubs"?
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Find out the exact number of students in all 3 clubs(total number of unique students)
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