unknown - a number or value we do not know

2 Unknown Word Problems

Free 2 Unknown Word Problems Calculator - Solves a word problem based on two unknown variables

3 unknowns using Cramers Rule

Free 3 unknowns using Cramers Rule Calculator - Solves for 3 unknowns with equations in the form ax + by + cz = d using Cramers Method.

4 unknowns using Cramers Rule

Free 4 unknowns using Cramers Rule Calculator - Solves for 4 unknowns with equations in the form aw + bx + cy + dz = e using Cramers Method.

76 decreased by twice a number. Use the variable n to represent the unknown number

76 decreased by twice a number. Use the variable n to represent the unknown number.
Twice a number (n) means we multiply the unknown number n by 2:
2n
76 decreased by twice a number means we subtract 2n from 76 using the (-) operator
[B]76 - 2n[/B]

A random sample of 144 with a mean of 100 and a standard deviation of 70 is known from a population

A random sample of 144 with a mean of 100 and a standard deviation of 70 is known from a population of 1,000. What is the 95% confidence interval for the unknown population?
[URL='http://www.mathcelebrity.com/normconf.php?n=144&xbar=100&stdev=70&conf=95&rdig=4&pl=Large+Sample']Large Sample Confidence Interval Mean Test[/URL]
[B]88.5667 < u < 111.4333[/B]

A random sample of n = 10 flash light batteries with a mean operating life X=5 hr. And a sample stan

A random sample of n = 10 flash light batteries with a mean operating life X=5 hr. And a sample standard deviation S = 1 hr. is picked from a production line known to produce batteries with normally distributed operating lives. What's the 98% confidence interval for the unknown mean of the working life of the entire population of batteries?
[URL='http://www.mathcelebrity.com/normconf.php?n=10&xbar=5&stdev=1&conf=98&rdig=4&pl=Small+Sample']Small Sample Confidence Interval for the Mean test[/URL]
[B]4.1078 < u < 5.8922[/B]

A student and the marine biologist are together at t = 0. The student ascends more slowly than the m

A student and the marine biologist are together at t = 0. The student ascends more slowly than the marine biologist. Write an equation of a function that could represent the student's ascent. Please keep in mind the slope for the marine biologist is 12.
Slope means rise over run.
In this case, rise is the ascent distance and run is the time.
12 = 12/1, so for each second of time, the marine biologist ascends 12 units of distance
If the student ascends slower, than the total distance gets reduced by an unknown factor, let's call it c. So we have the student's ascent function as:
[B]y(t) = 12t - c[/B]

Binomial Multiplication (FOIL)

Free Binomial Multiplication (FOIL) Calculator - Multiplies out the product of 2 binomials in the form (a + b)(c + d) with 1 unknown variable.

This utilizes the First-Outside-Inside-Last (F.O.I.L.) method.

This utilizes the First-Outside-Inside-Last (F.O.I.L.) method.

Equation and Inequalities

Free Equation and Inequalities Calculator - Solves an equation or inequality with 1 unknown variable and no exponents as well as certain absolute value equations and inequalities such as |x|=c and |ax| = c where a and c are constants. Solves square root, cube root, and other root equations in the form ax^2=c, ax^2 + b = c. Also solves radical equations in the form asqrt(bx) = c. Also solves open sentences and it will solve one step problems and two step equations. 2 step equations and one step equations and multi step equations

If 3 pounds of apples cost 0.90, how much will 10 pounds cost?

Set up a proportion of apples to cost, where a is the unknown cost amount of apples for 10 pounds
3/0.90 = 10/c
Use our [URL='http://www.mathcelebrity.com/prop.php?num1=3&num2=10&den1=0.90&den2=c&propsign=%3D&pl=Calculate+missing+proportion+value']proportion calculator[/URL]:
[B]c = 3[/B]

If you triple me, subract 7, and add 4 you get 42. What number am i?

If you triple me, subract 7, and add 4 you get 42. What number am i?
Start with an unknown number, "x".
Triple me
3x
Subtract 7
3x - 7
Add 4
3x - 7 + 4
You get 42
3x - 7 + 4 = 42
Simplify:
3x - 3 = 42
Run this through our [URL='https://www.mathcelebrity.com/1unk.php?num=3x-3%3D42&pl=Solve']equation calculator:[/URL]
x = [B]15[/B]

Kimberly wants to become a member of the desert squad at a big catering company very badly, but she

Kimberly wants to become a member of the desert squad at a big catering company very badly, but she must pass three difficult tests to do so. On the first Terrifying Tiramisu test she scored a 68. On the second the challenging Chocalate-Sprinkled Creme Brulee she scored a 72. If kimberly needs an average of 60 on all three tests to become a member on the squad what is the lowest score she can make on her third and final test
This is a missing average problem.
Given 2 scores of 68, 72, what should be score number 3 in order to attain an average score of 60?
[SIZE=5][B]Setup Average Equation:[/B][/SIZE]
Average = (Sum of our 2 numbers + unknown score of [I]x)/[/I]Total Numbers
60 = (68 + 72 + x)/3
[SIZE=5][B]Cross Multiply[/B][/SIZE]
68 + 72 + x = 60 x 3
x + 140 = 180
[SIZE=5][B]Subtract 140 from both sides of the equation to isolate x:[/B][/SIZE]
x + 140 - 140 = 180 - 140
x = [B]40[/B]

Natalie made a deal with a farmer. She agreed to work for an entire year and in return, the farmer w

Natalie made a deal with a farmer. She agreed to work for an entire year and in return, the farmer would give her $10,200 plus a prize pig.
After working for 5 months, Natalie decided to quit. The farmer determined that 5 months of work was equal to $3375 plus the pig. How much money was the pig worth?
The value of a year's work is $10,200 plus a pig of unknown value. The farmer took away $6825 because Natalie worked 5 months. If Natalie worked 7 more months, she would have been paid the additional $6825.
6825/7 months work = $975 per month
A full year's work is $975 * 12 = $11,700
Pig value = Full years work - payout
Pig value = 11,700 - 10,200
Pig value = [B]1,500[/B]

Peter was thinking of a number. Peter doubles it and adds 0.8 to get an answer of 31. Form an equati

Peter was thinking of a number. Peter doubles it and adds 0.8 to get an answer of 31. Form an equation with x from the information.
Take this algebraic expression in parts, starting with the unknown number x:
[LIST]
[*]x
[*][I]Double it [/I]means we multiply x by 2: 2x
[*]Add 0.8: 2x + 0.8
[*]The phrase [I]to get an answer of[/I] means an equation. So we set 2x + 0.8 equal to 31
[/LIST]
Build our final algebraic expression:
[B]2x + 0.8 = 31[/B]
[B][/B]
If you have to solve for x, then we [URL='https://www.mathcelebrity.com/1unk.php?num=2x%2B0.8%3D31&pl=Solve']type this equation into our search engine[/URL] and we get:
x = 15.1

Simultaneous Equations

Free Simultaneous Equations Calculator - Solves a system of simultaneous equations with 2 unknowns using the following 3 methods:

1) Substitution Method (Direct Substitution)

2) Elimination Method

3) Cramers Method or Cramers Rule Pick any 3 of the methods to solve the systems of equations 2 equations 2 unknowns

1) Substitution Method (Direct Substitution)

2) Elimination Method

3) Cramers Method or Cramers Rule Pick any 3 of the methods to solve the systems of equations 2 equations 2 unknowns

Substitute the given values into given formula and solve for the unknown variable. S=4LW + 2 WH; S=

Substitute the given values into given formula and solve for the unknown variable. S = 4LW + 2 WH; S= 144, L= 8, W= 4. H=
S = 4LW + 2 WH
Substituting our given values, we have:
144 = 4(8)(4) + 2(4)H
144 = 128 + 8H
Using our [URL='http://www.mathcelebrity.com/1unk.php?num=128%2B8h%3D144&pl=Solve']equation calculator[/URL], we get:
[B]H = 2[/B]

The difference of a number times 3 and 6 is equal to 7 . Use the variable w for the unknown n

The difference of a number times 3 and 6 is equal to 7 . Use the variable w for the unknown number.
The phrase a number uses the variable w.
3 times w is written as 3w
The difference of 3w and 6 is written as 3w - 6
Set this equal to 7
[B]3w - 6 = 7
[/B]
This is our algebraic expression. To solve this equation for w, we [URL='http://www.mathcelebrity.com/1unk.php?num=3w-6%3D7&pl=Solve']type the algebraic expression into our search engine[/URL].

Unknown Number

Free Unknown Number Calculator - Determines the unknown number needed to make an equation true.

Use c for unknown variable : Sam's age plus twice his age

Use c for unknown variable : Sam's age plus twice his age
Sam's age:
c
Twice his age means we multiply c by 2:
2c
Sam's age plus twice his age
[B]c + 2c[/B]

What is the value of an unknown number of nickels expressed in cents?

What is the value of an unknown number of nickels expressed in cents?
1 nickel = 5 cents
n nickels = [B]5n[/B] cents

When 39 is added to a number, the result is 40 times the number. Find the number. Let n be the unkn

When 39 is added to a number, the result is 40 times the number. Find the number. Let n be the unknown number. Write the translated equation below.
[LIST=1]
[*]39 added to a number is written as n + 39
[*]40 times the number is written as 40n
[*]The result is means we have an equation, so set (1) equal to (2)
[/LIST]
n+ 39 = 40n
Running [URL='http://www.mathcelebrity.com/1unk.php?num=n%2B39%3D40n&pl=Solve']n + 39 = 40n through the search engine[/URL], we get[B] n = 1[/B].