a vertical stick 2m long cast a shadow 1m long,at the same time a building cast a shadow 15m long.How tall is the building?

Cross multiply and solve for x.

2/1 = x/15

To find the height of the building, we can set up a proportion using the lengths of the shadows.

Let's assign variables to the unknowns:
- Height of the building = B (in meters)

Given information:
- Length of the vertical stick = 2 meters
- Length of the vertical stick's shadow = 1 meter
- Length of the building's shadow = 15 meters

We can set up the proportion using the ratios of the heights to the lengths of their respective shadows:
B / 15 = 2 / 1

Now, we can solve for B by cross-multiplying and then dividing:
B = (2 * 15) / 1

Simplifying further,
B = 30 meters

Therefore, the height of the building is 30 meters.