If it costs $0.15 per kwh how much did it cost to leave your light on for those 8 hrs?

1141km

Explanation:

Given the following :

Distance due west = 915m

Distance due North = 681m

The magnitude of the Displacement =?

The information above produces a right angle triangle and the magnitude of the displacement can be calculated using Pythagoras rule :

The Magnitude of the woman's Displacement represents the hypotenuse of the triangle:

From Pythagoras :

Hypotenus = √(opposite)^2 + (adjacent)^2

Hypotenus = √(915)^2 + (681)^2

Hypotenuse = √1300986

Hypotenuse= 1140.6077

The magnitude of woman's displacement =  1140.6077 = 1141(to the nearest kilometer).