Formulas You’ll Need for the GMAT™ Quantitative Section’s Statistics and Problem Solving Questions
When you’re solving problems in the GMAT™ Quantitative Section, you need to be both fast and accurate. You cannot choose just one. If you want to ace the test, you’ll need to be able to understand the problem quickly, figure out the process to solve it, and actually perform the necessary calculations in less than 2 minutes. There are 31 questions in all and just 61 minutes to solve them.
To achieve that, you need to have the equations you need ingrained in your brain, and we have the resources you need. In the following chart, you’ll find the essential equations for the GMAT™ Quantitative Section Statistics and Problem Solving Questions. You’ll find formulas relating to the other types of questions on this section of the test here:
Use them to solve our free sample problems.
For more indepth information, check out our free study guide
Statistics and ProblemSolving
Category  Formula  Symbols  Comment 

Statistics and Problem Solving 
\(d=r \cdot t\) \(w=r \cdot t\) \(W=r \cdot t\) 
d = distance w = wage W = Work done r = rate t = time 

Statistics and Problem Solving 
\(TW=WA+WB\)  TW = Total work done WA = Work done by A WB = Work done by B 
Combined Work 
Statistics and Problem Solving 
\(\dfrac{1}{t} = \dfrac{1}{tA} + \dfrac{1}{tB}\)  t = total time tA = time consumed by A tB = time consumed by B 
Combined Work 
Statistics and Problem Solving 
\(Du=Su \cdot \dfrac{Du}{Su}=Su \cdot CF\)  Du = Desired Unit Su = Starting Unit CF = Conversion Factor 
Multiple steps may be needed. 
Statistics and Problem Solving 
\(a \cdot b\% =a \cdot \frac{b}{100}\)  a = any real number b% = any percent 
Remember to simplify if necessary 
Statistics and Problem Solving 
\(\% = \frac{\vert ba \vert }{b} \cdot 100= \frac{c}{b} \cdot 100\)  % = % increase or decrease a = new value b = original value c = amount of change 

Statistics and Problem Solving 
\(\overline{x}= \dfrac{\Sigma x_i}{n}\)  \(\overline{x}\) = mean \(x_i\) = value of each measurement n = number of measurements 

Statistics and Problem Solving 
\(Md=(\dfrac{n+1}{2})^{th} term\)  Md = median n = number of measurements (odd) 

Statistics and Problem Solving 
\(Md=\dfrac{(\frac{n}{2})^{th} term + (\frac{n+1}{2})^{th} term }{2}\)  Md = median n = number of measurements (even) 

Statistics and Problem Solving 
\(s=\sqrt{\Sigma(x_i\overline{x})^2/(n1)}\)  s = standard deviation \(\overline{x}\) = mean \(x_i\) = value of each measurement n = number of measurements 

Statistics and Problem Solving 
\(V=s^2\)  v = Variance s = standard deviation 

Statistics and Problem Solving 
\(CV=RSD=100 \cdot \dfrac{s}{\overline{x}}\)  CV = Coefficient of variation RSD = Relative standard deviation s = standard deviation 

Statistics and Problem Solving 
\(P(n, r)=\dfrac{n!}{(nr)!}\)  P = number of permutations n = total number of objects r = number of objects to be chosen 

Statistics and Problem Solving 
\(C(n, r) = \dfrac{n!}{r! \cdot (nr)!}\)  C = number of combinations n = total number of objects r = number of objects to be chosen 

Statistics and Problem Solving 
\(p = \dfrac{d}{t}\)  p = probability of an event d = number of ways desired event can occur t = total number of possible events 

Statistics and Problem Solving 
\(x_n = x_1 + d(n1)\)  \(x_n = nth\) element of an arith. sequence \(x_1 = 1st\) element of an arith. sequence d = common difference 
Arithmetic Sequence 
Statistics and Problem Solving 
\(x_n = x_1 \cdot r^{(n1)}\)  \(x_n = nth\) element of a geom. sequence \(x_1 =\) first element of a geom. sequence d = common difference 
Geometric Sequence 
Statistics and Problem Solving 
\(SI = P \cdot IR \cdot t\)  SI = Simple Interest P = Principal (amount borrowed) IR = Interest Rate t = time (in same units as IR) 

Statistics and Problem Solving 
\(A_{SI} = P + SI = P \cdot (1+(IR \cdot t))\)  \(A_{SI}\) = Future value to be paid (for SI) P = Principal (amount borrowed) SI = Simple Interest IR = Interest Rate t = time (in same units as IR) 

Statistics and Problem Solving 
\(A_{CI} = P \cdot (1 + \frac{IR}{n})^{n \cdot t}\)  \(A_{CI}\) = Future value to be paid (for CI) P = Principal (amount borrowed) IR = Interest Rate n = Number of times interest is compounded per unit of time t = time (in same units as IR) 
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