SOLUTION: Heater A warms a room from 40 degrees to 70 degrees in 5 hours. Heater B can do this job in 7 hours. Heater A alone is started but breaks down in 2.5 hours. How long will it take h

Question 1032872: Heater A warms a room from 40 degrees to 70 degrees in 5 hours. Heater B can do this job in 7 hours. Heater A alone is started but breaks down in 2.5 hours. How long will it take heater B to finish the job.
* a chart would be especially helpful*
Answer by josgarithmetic(39625) (Show Source): You can put this solution on YOUR website!
The exercise is intended as a uniform rates problem, each "worker" being a heater, working at its own rate. You can make a chart or table of rates.

One job is "warm the room air from 40 to 70 degree".

HEATER          RATE

A               1/5

B               1/7

Another chart may be what you want, but the rest of the solution will be through equations only. The rule to use will be RT=J relating rate, time, job.

for the heaters working separately, to do ONE JOB. The unknown time for heater B to work to finish the job is x.

Once that is understood, solving for unknown time x is uncomplicated arithmetic.
RELATED QUESTIONS
A heater raises the temperature 15 degrees in 24 minutes. With a second heater also in... (answered by josgarithmetic)

Although I know the answer to the following problem, I need to write it as a function and (answered by stanbon)

A water heater ha sa diameter of 18 inches. It sits in a drain pan that has a diameter of (answered by Alan3354)

if it take 2 men 8 hours to install a water heater what would be the total man... (answered by josmiceli)

how many lengths of heater hose, each 5 1/4 inches long, can be cut from a 12 foot roll? (answered by ewatrrr)

For a certain hot-water heater, the increase in heating expenses is directly proportional (answered by stanbon)

Shower temperature at the Oxnard Health Club showers is regulated automatically. The... (answered by ikleyn)

A homeowner in a sunny climate has the opportunity to install a solar water heater in his (answered by jorel555)

A water heater consumed 18 kWh of electrical energy when it is used for 15 minutes per... (answered by ikleyn)