What are the 95% confidence limits for the variance of the temperatures from 1868-1877 using the equal tails method."
a) Lower limit: 3.42, Upper limit: 15.78
b) Lower limit: 4.56, Upper limit: 16.91
c) Lower limit: 5.01, Upper limit: 17.35
d) Lower limit: 6.12, Upper limit: 18.44