Page 81 - Calculating Agriculture Cover 20191124 STUDENT - A

CH 6] Calculating Agriculture 6-3

Solution: There are 12 inches in 1 foot. In t feet there are t times as many inches. Therefore, the
formula is:

I = 12 t

This can be read as “the number of inches is 12 times the number of feet.”

Example B: If one 600 pound steer costs $650, how much will b steers cost?

Solution: Each steer costs $650. Then the total cost (T) of b steer’s will cost $650 x b, the
number of steers. As a formula it is written as:

T = $650 x b or T= ($650)(b) or T=$650 b

Example C: If a vehicle travels d miles at a rate or r miles per hour in t hours, write a formula to
calculate the time (t) to travel. Remember that d = rt.

Solution: Using the formula d = rt, then to calculate t the formula becomes:
d/r = t

Example D: Write as a formula: The average (A) of 3 numbers equals their sum divided by 3.

Solution: Let the numbers be represented as M, N, and O, respectively. Then:

M + N + O
A = —————
3

Example E: Translate into a formula: The selling price (S) of an item that is equal to its cost (C)
added to the profit (P) made on it.

Solution: S = C + P

Example F: Write as a formula: The perimeter (P) of a square is equal to 4 times the length of its
side.
6
Solution: If we let g be the length of the side of the square, then the formula is:
P = g + g + g + g.
This can also be stated as:
P = 4 g, read as “P equals 4 times the length of side g.”

———————— Rule to Remember —————————
A formula is an equation which contains letters as symbols that will express a
rule a relationship or a mathematical principle.

Variables and Constants

A vehicle purchased one year ago would not sell today for the same amount. As time marches
on, the re-selling price becomes smaller. As the age of the vehicle changes, its value changes; simply
put, the re-selling price of the vehicle depends on its age. The age and selling price of this vehicle are
termed variables. A variable is a quantity that changes in value. As the re-selling price of the vehicle

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