Question

The mean of 10 values is 19. If further 5 values are

included the mean becomes 20. What is the mean
these five additional values?
a) 10
b) 15
c) 11
d) 22​

Answer 1

22

Explanation:

Pretend the 10 values in the first sentence are a,b,c,d,e,f,g,h,i,j

Pretend the addition 5 values is k,l,m,n,o

So the mean of all the 15 data is (a+b+c+d+e+f+g+h+i+j+k+l+m+n+o)/15=20

So the sum of all 15 data is a+b+c+d+e+f+g+h+i+j+k+l+m+n+o=300 since 15(20)=300

Now let's look at the first 10: We have their mean so we can write:

(a+b+c+d+e+f+g+h+i+j)/10=19

so a+b+c+d+e+f+g+h+i+j=190 since 10(19)=190

So that means using our first sum equation and our equation sum equation we have

190+k+l+m+n+o=300

k+l+m+n+o=300-190

k+l+m+n+o= 110

So the average of those 5 numbers mentioned in your problem is 110/5=22