Sales from a Chain of Computer Stores Are Normally Distributed

Sales from a chain of computer stores are normally distributed, with an average monthly sales volume of $280,560.Estimating the amount of monthly variability in sales is of interest to help anticipate normal income fluctuations.A random sample of 8 months' sales data yields a standard deviation of $10,423.What is a 98% confidence interval for the standard deviation of monthly sales volume?

A) ($172,694.71, $666,866.84)
B) ($6152.47, $21,491.21)
C) ($6123.96, $27,725.40)
D) ($6415.73, $24,774.57)