Question

The mean of 19 numbers is 20 if the mean of first 10 numbers is 18 and the mean of last 10 number is 22. Find the 10th number? ​

Answer 1

Answer:

from first sentence,we can understand that,the sum of 19 numbers=19*20=380,

10the number is repeated for 2 times,

so, mean of first 10 numbers=18,the sum of first10 numbers=10*18=180,

the mean of second 10 numbers=22,so sum of second 10 numbers=10*22=220,

if we add these two. numbers 180+220=400

so,difference=20,by this we can understand that the10that number is 20(as it is repeated for two times)