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12 Cards in this Set
- Front
- Back
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What is the procedure for finding the last digit in a multiplication?
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1. Multiply the unit digits together.
Example: 5^2*9^2*4^3 5^2=25 9^2=81 4^3=64 Therefore 5*1*4=20, thus the last digit is 0. |
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What happens when the numerator and denominator both increase by the same value?
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When the numerator and denominator increase by the same value the fraction gets closer to 1.
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What is a quick way to compare two fractions?
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Cross multiply.
Example. Which fraction is greater 7/9 or 4/5? Cross multiply: 7*5 4*9 35 < 36 Thus 4/5 is greater. |
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What is benchmarking and when do you use it?
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When you find seemingly complicated fractions on the GMAT, use Benchmark Values to make sense of them.
Example: Which is greater: 127/355 or 162/320. If yu recongize that 127 is less than half of 255 and 162 is more than half of 320 you will save yourself a lot of cumbersome computation. |
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What is the simple interest formula?
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principal * rate * time.
Example: $5000 invested for 6 months at an annual rate of 7% will earn $175 in a simple interest. Principal = $5000, Rate = 7%, or 0.07, Time = 6 months or 0.5 years. PRT = 5000*0.07*0.5=175 |
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What is the compound interest formula?
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P*(1+r/n)^nt
P is principal r is rate n is number of times per year t is number of years. 5000 invested for 1 year at a rate of 8% compounded quarterly will earn approximately 412. 5000*(1+0.08/4)^4*1=5412. |
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Chemical Mixture problem.
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Example.
500 ml solution is 20% alcohol by volume. If 100 ml of water is added what is the new concentration of alcohol. Original solution Substance Amount Percentage Alcochol 100ml 20% Water 400ml 80% Total 500ml 100% New solution Substance Amount Percentage Alcochol 100ml Water 500ml Total 600ml 100ml/600ml=16.6% |
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Express as a decimal:
1/8? |
0.125
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Express as a decimal:
1/6? |
0.166
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Express as a decimal:
5/4? |
1.25
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Express as a decimal:
4/3? |
1.33
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1/16
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0.0625
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