A biologist measured the rate of contractions of contractile vacuoles in a freshwater Paramecium with the organism surrounded by sucrose solutions with a range of different concentrations. Sucrose concentration (mol/L) Rate of Contractions (per minute)

0.00mol/L 16 per minute

0.05mol/L 13 per minute

0.10mol/L 8 per minute

0.15mol/L 5 per minute

0.20mol/L 1 per minute

0.25mol/L 0 per minute

0.30mol/L 0 per minute

0.35mol/L 0 per minute

When the Paramecium was returned to its natural habitat in pondwater the rate of contraction of the vacuole was 14.5 per minute. Estimate the solute concentration (osmolarity) of the pond water.