Question

15 numbers have the mean 9 .the sum of the 15 numbers is

Answer 1

Answer:

9

.

Explanation:

Let  

¯

x

i

be the mean of a group  

G

i

of  

n

i

observations,

where,  

i

=

1

,

2

,

3

,

...

,

m

.

Then, the mean  

¯

x

of the combined group

G

=

G

1

∪

G

2

∪

G

3

∪

...

∪

G

m

is given by,

¯

x

=

Σ

i

=

m

i

=

1

n

i

¯

x

i

Σ

i

=

m

i

=

1

n

i

.

We have,  

n

1

=

3

,

n

2

=

4

,

n

3

=

5

,

¯

x

1

=

7

,

¯

x

2

=

8

,

¯

x

3

=

11

.

Hence,  

¯

x

=

3

⋅

7

+

4

⋅

8

+

5

⋅

11

3

+

4

+

5

=

108

12

=

9

, as derived by

Answer 2

Answer:

18

Step-by-step explanation:

M = sum of all 15 terms / 2

9 = sum of all 15 term /2

18 = sum of all 15 terms

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