Does the growth of trees vary more when the trees are young? The international

Does the growth of trees vary more when the trees are young? The international tree ring data base collected data on a particular 440 year old douglas fir
tree. The standard deviation of the annual tree growth in the trees first 80 years of life was .8 millimeters per year. Assume that the population is normal.
We are interested in testing whether the population standard deviation of annual ring growth in the trees later years is less than 0.0 mm/year. The sample
variance of the ring growth for a random sample of size 100 taken from the trees later years =.3136 square mm. Use hypothesis testing to solve.