Question

The mean score of 25 observations is 80 and the mean score of another
55 observations is 60. Determine the mean score of the whole set of
observations.
​

Answer 1

$\LARGE{ \underline{ \orange{ \sf{Required \: answer:}}}}$

The mean of score of two separate number of observations is given to us. We have to find the mean of both the sets.

GiveN:

• Number of observations = 25
• Mean score = 80

Total score of set 1 = 25 × 80 = 2000

• Number of observations = 55
• Mean score = 60

Total score of set 2 = 55 × 60 = 3300

Now from the above:

• Total no. of obs. = 25 + 55 = 80
• Total score = 2000 + 3300 = 5300

Formula for finding Mean:

$\large{ \because{ \underline{ \boxed{ \rm{mean \: score= \frac{total \: score}{no. \: of \: observations} }}}}}$

Substituting the values,

⇛ Mean score = 5300 / 80

⇛ Mean score = 66.25 (Answer)

Answer 2

Answer:

$\huge \underline {Answer}$

Question

The mean score of 25 observations is 80 and the mean score of another

55 observations is 60. Determine the mean score of the whole set of

observations.

Given

➡️ Total observation - 25

➡️ Mean score - 80

To find

the mean score of the whole set of observations.

Solution

Total score of set 1 = 25 × 80 = 2000

Number of observations = 55

Mean score = 60

Score of set 2 = 55 × 60

So ,

Total no. of observation = 25 + 55 = 80

Total score = 2000 + 3300 = 5300

Formulae

Mean = Total score / number of observation

Mean = 5300 / 80

Mean = 66.25