Respuesta :

9514 1404 393

Answer:

  -15/16  

Step-by-step explanation:

The sum of a geometric series with first term a1 is ...

  S = a1/(1 -r)

Then the common ratio (r) is ...

  r = 1 -a1/S

For the given values, the ratio is ...

  r = 1 - 124/64 = -15/16

The common ratio is -15/16.