We are given the following in the question:
Let x be the total number of sparkling cans of water used in a day.
The family uses more than 15 cans each day so inequality becomes,
Number of cans in 30 days
The family buys case of water with 24 cans in each case.
Number of cans used in a day is more than 15, so approx number of cans used in 30 days will be =
Thus, the family buys around 19 cases or more of sparkling water in 30 days.
The conversion factor is 180/pi
13 pi /6 * 180/pi
There are 5 significant figures.