The terms \(140, a, \frac{45}{28}\) are the first, second and third terms, respectively, of a geometric sequence. If \(a\) is positive, what is the value of \(a\) ?
Sqrt[ (45/28) / 140] =3/28 - Common ratio.
3/28 x 140 = 15 - the 2nd term "a"
140, a, 45/28
Let r be the common ratio...so
140r = a ⇒ r = a /140
So..this implies that
a (a / 140) = 45/28
a^2 = (140*45) / 28
a^2 = 5 * 45
a^2 = 225
a = 15
+885 
