Practice 2.3 – Formulas
Name _________________________________
Solve the formula for the specified variable.
1. d = rt for r
2. I = Prt for t
3. C = d for d
4. V =  r 2 h for h
5. y = mx  b for x
6. A =
1
bh for b
2
7. S = P  Prt for t
8. Ax  By = C for y
9. 3 x − y = 7 for y
10. 3 x  2 y = 12 for y
11. z = 13  2 x  y  for x
12. m = 19 − 5 x − n for n
13. While solving 2 A = ah  bh for h, Lea writes h =
2 A − ah
. What is her mistake?
b
Solve the problem and write your answer as a complete sentence.
14. The formula d = 344 t can be used to determine how far d, in meters, sound travels through room temperature air in t seconds. At a large concert, fans near the back of the crowd experienced a 0.9 second time lag between the time each word was spoken on stage and the time the sound reached their ears. How far were these fans from the stage?
15. Contractors in the Northwest use the formula B = 30f to determine the minimum furnace output B, in British thermal units (Btu's), for a well­insulated house with f square feet of flooring. Determine the minimum furnace output for a house with 1800 square feet that is well­insulated.
16. Air temperature drops about 1 degree Celsius (C) for each 100 meter rise above ground level, up to 12 kilometers. If the ground level temperature is t degrees Celsius, write a formula for the temperature T at an elevation of h meters.