Sesquiduplicate /(?)/

Ses·qui·du·pli·cate

Sesquiduplicate

a.
  1. Twice and a half as great (as another thing); having the ratio of two and a half to one.

Phrases & Compounds
Sesquiduplicate ratio
the ratio of two and a half to one, or one in which the greater term contains the lesser twice and a half, as that of 50 to 20.