21 chaperones are needed for 420 students.
Step-by-step explanation:
No. of juniors = 148
No. of seniors = 272
Total = 148+272 = 420 students
3 chaperones = 60 students
1 chaperone = 
Ratio of chaperon to students = 1:20
Let,
x be the number of chaperons for 420 students.
Ration of chaperones to students = x:420
Using proportion
Ratio of chaperones to students :: Ratio of chaperons to students

Product of mean = Product of extreme

Dividing both sides by 20

21 chaperones are needed for 420 students.
Keywords: ratio, proportion
Learn more about ratios at:
#LearnwithBrainly
Answer:
3,4,5 are the famous triplets
Answer:
500 miles
Step-by-step explanation:
70.5 : 2 = 35.25
so 1 galon is 35.25 miles
35.25 x 15 = 528.75 miles
and rounded to the nearest hundredth is 500 miles