Dunnhumby Interview Question | Street Lights
Question
How many street lights are there in India? You can assume any missing data but it should be based on the facts.
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The number of street lights in india
ASSUMPTIONS
let us assume total area covered by india = 2000 thousand km per sqaure
out of which 80% is land and the reamining 20% includes water bodies and forest in india.
let us assume that the land covered is further divided into two categories –
—Advanced cities and remote areas –
The advanced cities covers 60% of land, where as remote areas covers 40%.
let us assume that in advance cities on an average have 10 street lights per 1 km/sq.
and remote areas on an average have 5 street lights per 1 km/per square
So, total land area = 2000 * (80/100) = 1600 thousand km per square
out of which land covered by forest and water bodies = 2000 *(20/100) = 400 thousand km per square
Thus, 1600 thousand km per square is further divided into-
The area covered by advanced cities = 1600 * (60/100) = 960 thousand km per square
The area covered by remote areas = 1600 * (40/100) = 640 thousand km per square
The street lights in advanced cities = (960,000)*10 = 9,600,000 street lights
The street lights in remote areas = (640,000)* 5 = 3,200,000 street lights
So, total street lights in india = (9,600,000 + 3,200,000) = 12,800,000 street lights