Answer: 1.1
Explanation:
Given expression : c = 1.1b, where c= total cost of b bottles of water.
Two variables are proportional if there is always a constant ratio between them, and that ratio is called the constant of proportionality.
Here, if we divide c by b , we get
Thus the constant ratio of total cost 'c' to number of bottles'b' is 1.1 :1.
Thus, the constant of proportionality here= 1.1.