20. The middle school track team consists of 7th and 8th graders. There are 79 seventh graders
which is 47% of the team. How many 8th graders are on the team?
89
79
82
16

Option A (89)

Step-by-step explanation:

Number of 7th graders :

Let x represent the total number of the team.

The expression will then be:

47% of x = 79

47 / 100 * x = 79

47x / 100 = 79

Cross Multiply.

47x = 79 * 100

x = 7900/47

x = 168.08

x = 168 (approximately)

Therefore, it means we have a total of 168 team members.

Numbers of 8th graders:

Total number of team members minus number of 7th graders

8th graders = 168 - 79

8th graders = 89

There are 89 8th graders on the team

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.