the avarage age of group of students in 15 years. when 5 more students joined the group the avarage age rose 1 year. the avarage age of the new students is.
Answers
Answer:
Explanation:
average= sum of observations/total number of observation.
in given question,
average=15
let,
sum of observations ie., sum of ages of students of class be x and total number of observation ie., number of students=y
average= sum of observations/total number of observation.
so,
x/y=15---------------equation 1
it is also given that,
if another 5 students join average increase by 1 ie., new average is 16.
Let,
sum of ages of 5 students be z.
Now,
sum of observations=x+z
total number of observation=y+5.
New average= x+z/y+5=16-----------equation 2
We know,
x/y=15
so x=15y-------------equation 3
We also know,
x+z/y+5=16
so x+z=16(y+5)
x+z=16y+80---------------equation 4
Now substitute value of x from equation 3 in equation 4,
so,
x+z=16y+80
15y+z=16y+80
z=16y-15y+80
z=y+80---------equation 5
average of age of new 5 students=z/5=y+80/5.