This question was previously asked in

UPSSSC Chakbandi Lekhpal Official Paper 3 (Held on : 1 Oct 2019 Shift 1)

Option 2 : 8

**Given:**

Mean of 6 observations = 10

Mean of 4 observations = 6

**Formula used:**

Mean = The sum of all observations/Number of observations

**Calculation:**

According to the question,

Mean = The sum of all observations/Number of observations

⇒ 10 = The sum of 6 observatiions/6

⇒ The sum of 6 observations = 60 ----(1)

Again, according to the question,

Mean = The sum of all observations/Number of observations

⇒ 5 = The sum of 4 observations/4

⇒ The sum of 4 observations = 20 ----(2)

Now, The mean of the mixed sets,

Mean = The sum of all observations/Number of observations

⇒ Mean = (60 + 20)/10

⇒ Mean = 8

**∴ The mean of the mixed set is 8.**