Answer: The average was 9 years old find the average age of both groups is 10 years old.
Step-by-step explanation:
Formula foe average : 
Given : The first group of students consists of 10 and their average age was 13 years old.
i.e.
(1)
The next group consisted of 30 students and their average was 9 years old.
i.e.
(2)
Then from (1) and (2) , the sum of both groups (first group and next group )students = 130+270 =400
Combined students of both groups (first and next group )= 10+30=40
Now , the average of both groups =

Hence, the average was 9 years old find the average age of both groups is 10 years old.
Answer:
x=4
Step-by-step explanation:
Answer:
−
8
5
=−0.62500
Step-by-step explanation:
I used something Imao-
Circumference of circle = 2 pi r
= 2 x 3.14 x 6
= 6.28 x 6
= 37.68 cm
Area of circle = pi r^2
= 3.14 x 6^2
= 3.14 x 36
= 113.04 cm^2