Answer:
40
Step-by-step explanation:
5 people in the room have 5*40 = 200 years altogether
a new person is X years old.
Now 6 people have (200 + x) years altogether.
Mean age of 6 people is (200+x)/6. and it is also = 40.
So,
(200+x)/6 = 40
200 + x = 240
x = 40
Solution: We have to choose two positions president and vice president from eight people. So, we need to use the Permutations formula in order to find the possible number of combinations.
The number of possible combinations is:
8P2 



Therefore the possible number of combination to select two positions from 8 people is 56
Answer: 8
Step-by-step explanation:
x/10 = 10/2.5
x = 8