A vertical photograph of a flat area having an average elevation of 250m above mean sea level was taken with a camera of focal length 25 cm. A section line AB 300 m long in the area measures 15cm on the photograph; a tower BP in the area also appears on the photograph.
The distance between images of top and bottom of the tower measures 0.5 cm on the photograph. The distance of the image of the top of the tower is 10 cm. The actual height of the tower is