Please use the table, which gives the total amounts of sales (in millions of dollars) for aerobic, basketball, cross-training, and walking shoes for the years 2005-2011. Determine which type of shoe shows greater variation: aerobic or cross-training.

Year Aerobic Basketball Cross-Training Walking

2005 263 878 1447 3673

2006 264 964 1525 4091

2007 284 892 1580 4197

2008 257 718 1628 4204

2009 225 741 2052 4416

2010 241 721 2109 4256

2011 250 729 2173 4299

Which type of shoe shows greater variation: aerobic or cross-training?

a)Aerobic shows greater variation with a standard deviation of ___ million dollars

b)Aerobic and cross-training have equal variances

c)Cross-training shows greater variation with a standard deviation of __ million dollars