The amount of balls in a given layer can be found by squaring the layer it is in
4 layers
top layer (1st) is 1
2nd is 4
3rd layer is 9
4th is 16
add them up
1+4+9+16=30
30 in that pyramid
Answer:
4.5cm
Step-by-step explanation:
Circumference = 2
r
28.3=2
r
28.3/2
=r
4.456
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
252.85 - 120.01 = 132.84
Meg would have spent $132.84.