Quant Efficiency Flashcards
A starts 35 miles west of B.
They both head east at the same time
A Travels 30mph
B travels 25mph
After how many hours will A and B meet?
Outline first thoughts
Both are heading the same direction.
A travels faster than B, and starts further
A will make up its distance lag at a rate of the difference of their speeds
35 = (5)(t=7)
7 hours
Translate:
In 5 years, A will be twice as old as B
A + 5 = 2(B+5)
NOT
A+5 = 2B
Average Rate:
Joe walks to work at 3mph and walks home at 2mph
without solving, is his average speed closer to 2mph or 3mph?
it will be closer to 2 because the same amount of distance was covered, yet more time was spent on his return trip (2mph)
if there are n terms listed from least to greatest, which value will be the median?
n is an odd number
(n+1)/2
ie 15 terms sorted
median = 16/2 = 8
DS Efficiency:
x = a + b. find the value of a
use b = (x-a) in every instance of b
How many ways can you re-arrange 2 even and 1 odd numbers
(3!)/(2!)
is m+z >0?
(1) m-3z > 0
(2) 4z-m > 0
Answer in 1m
Shortcut:
if > pointing in same direction then you can add.
(1) m>3z insufficient. what if they are both neg
(2) 4z > m insufficient. what if they are both neg
(1) + (2) z>0 sufficient
How many ways to pick 5 people out of 8?
8C5
or 8C3
How many ways to distribute 4 people in groups of 2?
(4C2)/2! = 3
(4C2) = 6 = how many unique pairs you can make from 4
x,y,z are all positive
x x/y?
Yes. Since x 3/4
x,y,z are all positive
x x/y?
No. Since x2/3
x,y,z are all positive
x>y OR (x/y > 1)
is (x-z)/(y-z) > x/y?
Yes. Since y>x, y decreases by a greater magnitude than does x, thereby increasing the number
5/4 -> 4/3
x,y,z are all positive
x>y OR (x/y > 1)
is (x+z)/(y+z) > x/y?
No. Since y>x, y increases by a greater magnitude than does x, thereby decreasing the number
3/2 -> 6/5
x,y,z are all positive
x x/y?
Multiplying or Dividing fraction by the same integer is the SAME
x,y,z are all positive
x x/y?
Multiplying or Dividing fraction by the same integer is the SAME
