For questions like these, where exactness is missing, I always tend to pick up smart numbers and check for a pattern. So here, we don't know the number of bottles present in each set. Hence, will consider 1 and 2.5 as the number of bottles in two consecutive sets. (SInce standard deviation between two sets of bottles is 1.5, which gives 1 + 1.5 = 2.5 ).

1. Cost of a set that has 1 bottle = (1 x 12.04) + 4.8 = 16.84
2. Cost of a set that has 2.5 bottles = (2.5 x 12.04) + 4.8 = 34.9

3. Difference of costs between these two = 34.90 - 16.84 = 18.06

This difference can be verified with any pair of sets which are one standard deviation away from each other. Hence the standard deviation of prices for each set is 18.06 .