The mean of the first eight prime numbers is 778
Find the mean of: (i) First eight natural numbers
(ii) First ten odd numbers
(iii) First five prime numbers
(iv) First six even numbers
(v) First seven multiples of 5.
(vi) Factors of 20
(vii) All prime numbers between 50 and 80
The mean of 15 observations is 8. If the mean of the first eight observations is 7 and that of the last eight observations is 10, then the value of the 8th observation is _____.