A Flag Staff 17.5m High Casts a Shadow of Length 40.25m. The Height of the Building Which Casts a Shadow of Length 28.75m Under Similar Condition will be?

• A flag staff 17.5m high casts a shadow of length 40.25m.

• The height of the building which casts a shadow of length 28.75m can be figure out in this way.

• Explanation

• Solution

Explanation

Two given entities here are

1. Height
2. Shadow

To determine the relation here, let suppose; the height of the building which casts a shadow of length 28.75m = y

Case

As we know that;

Shadow               Height

40.25m                17.5m

28.75                   y

• Shadow increases as height increased.
• Shadow decreases as the height decreased.

This clearly indicates that there is direct relation.

Direct/Indirect relation tells how the equation will be written.

40.25 : 28.75  ::  17.5 : y ________ (A)

After simplifying equation (A), we can easily figure out the value of y (y = 12.5m)

To Find

The height of the building which casts a shadow of length 28.75m = ?

Solution

Method I

Let suppose

The height of the building which casts a shadow of length 28.75m = y

Shadow               Height

40.25m                17.5m

28.75                   y

Relation between shadow and height is direct, so;

40.25 : 28.75  ::  17.5 : y

40.25 x y = 28.75x 17.5

40.25y = 503.125

y = 503.125/40.25

y = 12.5

The height of the building which casts a shadow of length 28.75m = 12.5m

Method II

40.25m shadow is casted by a flag of height = 17.5m

1m shadow is casted by a flag of height = 17.5/40.25

1m shadow is casted by a flag of height = 0.435m

28.75m shadow is casted by a building of height = 0.435 x 28.75

28.75m shadow is casted by a building of height = 12.5m

The height of the building which casts a shadow of length 28.75m = 12.5m

Conclusion

A flag staff 17.5m high casts a shadow of length 40.25m. The height of the building which casts a shadow of length 28.75m under similar condition will be 12.5m.