SOLUTION: Given Chicago is located at 42N and 88W and Detroit, MI is located at 42N and 83W. If the sun rises in Chicago at 6am (central standard time), when is the sun-rise time in Detroi

The fact that both cities have same latitude facilitates calculations.

    We should not make corrections to account for the latitude difference . . . 



The difference in longitudes is 5 degrees, which is  of the full Earth's rotation angle.


Hence, difference in times when sunrise happens  is    of 24 hours,   or


     of an hour =  of an hour =  of an hour =  of an hour = 20 minutes.


Sunrise at Detroit happens 20 minutes earlier than at Chicago, which corresponds to 6:40 of the Detroit's "eastern standard time".