A statistician claims that the standard deviation of the weights of firemen is less than 25 pounds. A sample of 20 randomly chosen firemen had a standard deviation of their weights of 26.2 pounds....

A statistician claims that the standard deviation of the weights of firemen is less than 25 pounds.  A sample of 20 randomly chosen firemen had a standard deviation of their weights of 26.2 pounds.  Assume the variable is normally distributed.  Atα = 0.05, what is the critical value for this test?

Round your answer to nearest thousandth (3 d.p.)  if necessary.