Let us draw the mean proportional of the following line segment and let us measure the values of the mean proportionals in each case with help of a scale:
10cm., 4cm.
Construction steps:
1. Draw a line segment AX with length greater than (10 + 4 = 14 cm).
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2. From A, mark a point B on AX such that AB = 10 cm and from B mark a point C such that BC = 4 cm
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3. Draw the perpendicular bisector of AC, such that it cuts AC at O.

4. Taking OA = OC as radius and O as center draw a semicircle.

5. Draw BD ⊥ AC such that, point D lies on the semicircle and

Here, BD is the mean proportional of AB and BC, and By construction AB = 10 cm and BC = 4 cm.
With the help of scale, we measure BD = 6.3 cm [Appx]