Formulas

A rectangle has m length and n width.  Write a formula for the area A and for the perimeter P of such a rectangle.

• A = mn

  P = m + n

• A = m + n

  P = mn

• A = mn

  P = 2m + 2n

• A = mn

  P = 4 + m + n

A water tank has a cuboid shape of w meters in width, L meters in length, and h meters in height.  Write down a formula of the amount of water it hold in liters W when completely full.  (Hint: 1 m³ is equal to 1000 liters)

• W = w x L x h

• W = w + L + h

• W = w³

• It's impossible to determine the amount of liters.

A plumber charges a call out fee of $20 dollars and $30 for each hour he works.  Write a formula for the total cost, T dollars, of a job that takes h hours.

• T = 50h

• T = 20h + 30

• T = 30h + 20

• T = 20 + 30

n cubes are stacked in a tower and placed on a table.  Faces touching the table or touching each other when the cubes are stacked are hidden from view and cannot be seen.  Derive the formula for the number of faces, f, that can be seen.

• f = 21

• f = 4n

• f = 4n + 2

• f = 4n + 1

Write down this formula. A number y is equal 4 plus 3 times a number x.

• y = 3 x + 4

• y = 12x

• y = 3 (x + 4)

• y = 7x

Write down the formula. A number x is equal to the difference between numbers a and b.

• x = a + b

• x = a - b

• x = ab

• x = a/b

The formula F = 1.8C + 32 can be used to convert temperature in C degrees Celsius to F degrees Fahrenheit. Convert 31 degrees Celsius to Fahrenheit. Round to the nearest degree.

• 89

• 86

• 87

• 88

if y = 2a + b - 4c. Find y if a = 1, b = 10, and c =2.5.

• 20

• 2

• 22

• 0

if x = a (b - c), find x when a = 4, b = 3, and c = -5.

• 32

• -8

• 12

• -32

if a = b - (c - d) + e. Find a if b = - 10, c = - 4, d = - 1 and e = - 2.

• 11

• -7

• 5

• -9