the mean of 25 observation is 65 and mean of next 10 observation is 62 find the mean of all 35 observation​

The required mean of all 35 observation is 64.1428

Given :

• the mean of 25 observations is 65
• the mean of next 10 observations is 62

To find :

the mean of all 35 observation​s

Solution :

The mean of 25 observations is 65 :

 65 = sum of 25 observations/25

sum of 25 observations = 65 × 25

sum of 25 observations = 1625

The mean of next 10 observations is 62 :

62 = sum of next 10 observations/10

sum of next 10 observations = 62 × 10

sum of next 10 observations = 620

The mean of all 35 observations :

Required mean = sum of 25 observations + sum of next 10 observations/35

Required mean = 1625 + 620/35

Required mean = 2245/35

Required mean = 449/7

Required mean ≈ 64.1428

Therefore, the mean of all 35 observation is 64.1428