Given:
The mean age of 5 people in a room is 26 years.
A person enters the room. The mean age is now 33.
To find:
The age of the person who entered the room.
Solution:
Formula for mean:

The mean age of 5 people in a room is 26 years.



The mean age is now 33. It means, the mean age of 6 people is 33.



Now, the age of the person who entered the room is
Required age = Sum of ages of 6 people - Sum of ages of 5 people
= 
= 
Therefore, the age of the person who entered the room is 68 years.
800 is 100% so 20 is 40% of 800.
For your answer the will be shown below
Unit rate= 9
Answer:
10 spiders and 12 ants
Step-by-step explanation:
You need to create two equations
s = # of spiders
a = # of ants
s + a = 22 heads
since each spider and ant has one head
8s + 6a = 152 legs
since every spider has 8 legs and every ant has 6
s + a = 22 can be turned into s = 22 - a
now use substitution
8(22 - a) + 6a = 152
176 - 8a + 6a = 152
176 - 2a = 152
24 = 2a
a = 12
now that you have the number of ants you can solve for the number of spiders
s + a = 22
s + 12 = 22
s = 10