Question

if the mean of 15 number is 18 and the mean of ten number is 13 find the mean of all the 25 number.

Answer 1

Answer:

Mean of all 25 numbers is 16.

Step-by-step explanation:

It is given that the mean of 15 numbers is 18.

So,

⇒ ( sum of 15 numbers ) / 15 = 18

⇒ Sum of 15 numbers = 18 x 15

⇒ Sum of 15 numbers = 270    ...( i )

It is given that the mean of other 10 numbers is 13.

So,

⇒ ( Sum of 10 numbers ) / 10 = 13

⇒ Sum of 10 numbers = 13 x 10

⇒ Sum of 10 numbers = 130

Now,

⇒ Total numbers = 15 + 10 = 25

⇒ Sum of all 25 numbers = sum of 15 numbers + sum of 10 numbers

Substitute values from ( i ) and ( ii ),

⇒ Sum of 25 numbers = 270 + 130

⇒ Sum of 25 numbers = 400

Then,

⇒ Mean of 25 numbers = ( sum of 25 numbers ) / ( total numbers )

⇒ Mean = 400 / 25

⇒ Means = 16

Therefore the mean of all 25 numbers is 16.