Problema Solution
a heater can raise the temperature of a gallon of water 10 degrees in 8 minutes. a second heater can raise the temperature of a gallon of water 10 degrees in 5 minutes. after the first heater had been operating for 1 minute, the second heater was turned on, and both were operated together. how long then did it take for both heaters to raise the temperature 10 degrees
Answer provided by our tutors
first heater heats 1 gallon 10 degrees in 8 minutes = 1.25 degrees in 1 minute
first heater heats 1 gallon 10 degrees in 5 minutes = 2 degrees in 1 minute
After 1 minute, temperature of water has been raised by 1.25 degrees. Then second heater is turned on. Both heaters working together heat by 3.25 degrees per minute.
10-1.25 = 8.75
Time to heat 10 degrees (after 2nd heater turned on) = 8.75/3.25 = 2.69 minutes = 2 minutes 41 seconds