A flagstaff 17.5 m high casts a shadow of length 40.25 m. The height of the building, which casts a shadow of length 28.75 m under similar conditions will be?

10 m

17.5 m

12.5 m

21.25 m

Let the height of the building be x meters.

Less lengthy shadow, Less in the height (Direct Proportion)

∴ 40.25 : 28.75 :: 17.5 : x ⇔ 40.25 × x = 28.75 × 17.5

x = 28.75 × 17.5/ 40.25 ⇒ x = 12.5