Q. 124.0( 5 Votes )

If a 1.5-m-tall girl stands at a distance of 3 m from a lamp post and casts a shadow of length 4.5 m on the ground, then the height of the lamp post is
A. 1.5 m

B. 2 m

C. 2.5 m

D. 2.8 m

Answer :

Untitled35.jpg


In the above figure, let PD be the girl, AB be the lamp post. Given that, the girl stands at a distance of 3 m from the lamp post. So BP = 3 m. Also the height of the girl is 1.5 m. So PD = 1.5 m. The shadow of the girl cast is of the length 4.5 m. So PC = 4.5 m. Then we have to find the height of the lamp post, that is, AB.


Now, BC = BP + PC = 3 + 3.5 = 7.5 m.


From ∆DPC,



ACB = DCP. So,


From, ∆ABC,



or,



or,



Hence the correct choice is C.

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