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Question
The shadow of a 3 m long stick is 4m long. At the same time of the day, if the shadow of a flagstaff is 24 m long, how tall is the flagstaff?
Solution
Let the length of flagstaff is x.
Shadow: Length :: Shadow : Length
4 m : 3 m :: 24 m : x
`4/3 = 24/x` .....`["If a, b, c and d are in proportion" a/b = c/d]`
`4 xx x = 3 xx 24` ......[By cross-multiplication]
`x = (3 xx 24)/4`
`x` = 18
Hence, the flagstaff is 18 m tall.
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