Every night, the average human body experiences an increase in melatonin levels, and then every day the levels decrease.

is this an example of a periodic event? explain.

Yes it is an example of a periodic event.

Step-by-step explanation:

If we represent this process by a continuous curve then we will observe that there will be ups and downs in the graph such that the cycle repeats itself every day

As we get maximum of the curve at night and minimum in the day and ir happens every day.

     Hence, this will represent an periodic event.

point a is the center of the circle that passes through points e, f, and g and the center of the circle that passes through points x, y, and z.

step-by-step explanation:

12: 00 p.m. to 7: 00 p.m. is a total of 7 hours.

4: 00 p.m. to 7: 00 p.m. is a total of 3 hours.

this means that from 4: 00 p.m to 7: 00 p.m. this represents 3/7 of what was lost from 12: 00 p.m. to 7: 00 p.m.

after knowing this, after doing 11,600 - 6,800 = 4,800

4,800 represents 3/7 of what was lost for 7 hours.

we then divide 4,800 by 3 which gets 1,600.

because we know that 1,600 represents 1/7 of how much water was lost, we just have to multiply by 7, which gets 11,200.   after adding 11,200 to how much water was left at 7: 00 p.m. which was 6,800. 11,200 + 6,800 = 18,000

this means that the pool originally had 18,000 gallons in the pool.

you can also check your work by doing 18,000 - 4(1600), which becomes           1800 - 6400 which gets you 11,600.