Consider two circular swimming pools. pool a has a radius of 12 feet, and pool b has a diameter of 7.5 meters. which pool has a greater circumference? how much greater? justify your answers.

The first thing we should do, it put both measurements into the same unit. I will use feet.
To convert meters to feet, we can use the formula:  1 m = 3.28 ft
so, we multiply both sides by 7.5
7.5 m = 24.6 ft
The diameter of pool B is 24.6 ft
The radius of pool A is 12 ft. To get diameter, simply multiply it by 2. 
12 ft * 2 = 24 ft
The diameter of pool A is 24 ft
Now that we know diameter, we can get the circumference
The equation for circumference is c = 2πr or c = πd
We have the diameter, so we will use the second one.
Plug in D in both equations, and we get 24π ft for pool A, and 24.4π ft for pool B
In decimals, it is approximately 75.398 ft for pool A and 76.655 ft for pool B
In this case, we see that pool B is bigger, by 0.4π ft, or 1.2566 ft 

1 ft is equivalent to 0.3048 m
swimming pool A radius is 12 feet
it's circumference is 22/7 x 24 feet= 75.43 feets
pool B circumference is 22/7 x 7.5 m= 23.57 m
in terms of meters pool A is 75.34x 0.3048=22.964 m
so pool B circumference is greater than pool A by 0.606 m

the law of definite proportions states samples of a compound will always contain the same proportion of elements by mass. in other words, a given compound will always contain the same elements in the same proportions by mass.the law of multiple proportions states when two elements combine with each other to form more than one compound, then the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.