Example 1

A signwriter has to erect a nameboard
with the letters BLC easily discernible from a distance of at least 1000 m. Allowing for
average acuity of 2 and adding a safety factor of 2, determine the minimum height of the
letters if the gap in the letter C is one-fifth the height of the letter.

Let the height of the gap be h meters after
taking the safety factor of 2.

The letter height = 5h = 5 x 0.29 = 1.45 m