Question

A vertical object 20 cm long casts a shadow 7 cm long on the ground. At the same time a pole casts a shadow 30 m long on the ground. Then find the approximate height of the pole.

• A. 60 m
• B. 85 m
• C. 92 m
• D. 70 m

Hint:

Height and shadow length are proportional for objects measured at the same time.

Answer 1

The Correct Option is B

Similar triangles give the same height to shadow ratio for the object and the pole.
Set up a direct proportion: pole height $= 30 \times \frac{20}{7}$.
$30 \times \frac{20}{7} = \frac{600}{7} = 85.71$ m, which rounds to about $85$ m.
\[\boxed{85 \text{ m}}\]