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Example Questions
Example Question #1808 : Sat Mathematics
With a head wind a plane can fly a certain distance in five hours. The return flight takes an hour less. How fast was the plane flying?
In general, .Â
The distance is the same going and coming; however, the head wind affects the rate. The equation thus becomes .
Solving for gives
.
Example Question #32 : Algebra
How much water should be added to of 90% cleaning solution to yield 50% cleaning solution?
Pure water is 0% and pure solution 100%. Let = water to be added.
 in general whereÂ
is the volume andÂ
is the percent.
So the equation to solve becomesÂ
and
Example Question #31 : Algebra
Solve and
This problem is a good example of the substitution method of solving a system of equations. We start by rewritting the first equation in terms of to getÂ
and then substutite theÂ
into the second equation to get
.Â
Solving this equation gives and substituting this value into one of the original equations gives
, thus the correct answer is
.
Example Question #71 : How To Find The Solution To An Equation
Joy bought some art supplies. She bought colored pencils for $1.25 per box and sketch pads for $2.25 each. Joy bought one more sketch pad than colored pencil boxes and spent $9.25. How many sketch pads did she buy?
Let = # of color pencil boxes andÂ
= # of sketch pads purchased.
So the equation to solve becomes .Â
Solving this equations leads to 2 colored pencil boxes and 3 sketch pads.
Example Question #31 : Algebra
This question deals with absolute value equations which will normally gives you two solutions.
You need to solve two sets of equations for absolute value problems:
and
Example Question #32 : How To Find The Solution To An Equation
Steve sells cars. His monthly salary is $1,000. He gets a $500 commission for each car he sells. If Steve wants to make $7,500 this month, how many cars would he have to sell?
Let = money earned andÂ
= number of cars sold
So
 and solving shows that he needs to sell 13 cars to make $7,500.
Example Question #33 : Algebra
A chemistry student needs to dilute some acid. How much pure water should be added to 2 gallons of 80% acid solution to yield 20% acid solution?
Let pure water = 0 % and pure acid = 100%
The general equation to use is:
 where
is the volume and
is the percent solution.
So the equation to solve becomes andÂ
gallons of pure water needs to be added to get a 20% acid solution.
Example Question #71 : How To Find The Solution To An Equation
The Widget Company makes widgets. The monthly fixed costs are $750. It costs $45 to make each widget. The widgets sell for $75 a piece.
What is the monthly break-even point?
The break-even point is where the costs equal revenue.
Let = # of widgets sold.
Costs:Â
Revenue:Â
So the equation to solve becomes
So the break-even point occurs when they sell 25 widgets.
Example Question #142 : Gre Quantitative Reasoning
The Widget Company makes widgets. The monthly fixed costs are $750. It costs $45 to make each widget. The widgets sells for $75 a piece.
The Widget Company wants to make a profit of $3,000. How many widgets must be sold?
Profits = Revenues - Costs
Revenue:Â
Costs:Â
Profit:
So the equation to solve becomes
So a $3,000 profit occurs when they sell 125 widgets
Example Question #131 : Equations / Inequalities
Sally sells custom picture frames. Her monthly fixed costs are $350. It costs $10 to make each frame. Sally sells her picture frames for $35 each.
How many picture frames must Sally sell in order to break even?
The break-even point is where the costs equal the revenues.
Let = # of frames sold
Costs:Â
Revenues:Â
Thus,
So 14 picture frames must be sold each month to break-even.
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