Answer:
13,888.88 gallons per second must be pumped from the adjacent Lake Michigan every second to supply the city.
Step-by-step explanation:
Gallons of water used by Chicago city in 1 day =

1 day = 24 hours
1 hour = 60 mins
1 min = 60 seconds

Gallons of water used by Chicago city in 86,400 seconds :
=

Gallons of water used by Chicago city in 1 second:

13,888.88 gallons per second must be pumped from the adjacent Lake Michigan every second to supply the city.