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Question
The area of a square filed is 8 hectares. How long would a man take to cross it diagonally by walking at the rate of 4 km per hour?
Solution
Given, area of square field = 8 hectares
= `8xx 0.01 [1 hectare= 0.01 km^2]`
=`0.08 km^2``
Now, area of square field =`"(side of square)"^2=0.08`
⇒ side of square field= `sqrt0.08=(2sqrt2)/10=sqrt2/5=km`
Distance covered by man along the diagonal of square field = length of diagonal
`sqrt2 "side"=sqrt2xxsqrt2/5=2/5 km`
Speed of walking = 4km/h
∴ Time taken = distance/ speed=`2/(5xx4)=2/20=1/10`
=`0.1` hour
=` 1/10xx60 min=6 minutes`
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