Assume that the concentration of stock is 1.0 M
And initial volume = 16.0 ml
final volume = 0.310 L or 310 ml
therefore
CiVi = CfVf
1.0 *16 ml = Cf * 310 ml
Cf = 1.0*16/310
= 0.052 M
Thus dilute solution is 0.052 M times dilute to concentrate solution