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