Powered ventilation systems should be turned on for how many minutes before starting the engine to ensure all gasoline vapors have been removed before ignition?

Minimum of four minutes.

Explanation:

The essence of this is to avoid explosions by removing flammable gases due to reaction with sufficient oxygen. Evaporation of gasoline creates vapors or fumes that are denser than air which would settle to the bottom of a vessel and cause explosion if enclosed areas are not properly ventilated to remove the fumes.

this means that the temperature of both substances will be equal

get the total number of pieces of fruit and divide it by 4 to get the average. the result is the answer to the problem. 14 total number of fruits and there are 4 members. 14 divided by 4 is equals to 3.5.