Why you so mean

Very easy ,

The even integers from $123$ to $987$ is $124,126,128....,984,986$ .

Lets Consider $124$ is $A$ and $986$ is $B$

so the Arithmatic Mean is $\frac{A+B}{2}$

And we got $\frac{1110}{2}$ = $\boxed{555}$

(123 + 987)/ 2 = 555

• primeiro vou ver qual o total de números que eu tenho: ------> 987 - 123 = 864

  total = 864 + 1 = 865

• agora vou descobrir quantos numero pares eu tenho nesse intervalo: visto que 1 até 10 temos 5 números pares, utiliza-se esse racicínio para obtermos a quantidade

quantidade = 479 números pares

• agora vamos pegar a somatória desses números pares:

somatória = $\frac{479(123 + 987)}{2}$

• O resultado da média será :

Média = $\frac{somatória}{quantidade}$ = $\boxed{555}$

The even numbers between 123 to 987 are : 124 , 126 .......... 984 , 986 . Let us consider 124 as A & 986 as B The arithmetic mean = /frac{ 124 + 986 }{ 2 } So the answer is 550

find thhe no: of terms using the a.p's nth term formula and then use the summation formula 555 :)

the no. of numbers= (987-123)+1=865 get the mean term= 865/2=432.5or 433rd term a 433=123+(433-1)1 a 433=123+432 a_433=555 mean=555

123+987=1110 1110/2=555

Primeiramente verifico quantos números são divisíveis por dois de 1 até 986, são 493. Depois verifico quantos números são divisíveis por 2 de 1 até 123, são 61. Logo diminuo 987 por 61 e obtenho 432 números divisíveis por dois de 123 até 987. Depois é só fazer a soma de todos esses números e então obtenho 239,760 e então divido por 432 obtendo 555, que é a média desejada.

as the range is [123,987],as even number(1st term=124,last term=986,d=2),

by using an arithmetic formulae,

Tn=a+(n-1)d 986=124+(n-1)2 986-124=2n-2 2n=986-124+2 n=864/2=432

so there are 432 terms,so for the mean,find the sum of the 1st 432 terms, =432/2 x (2(124)+(431)2) =239760

so for the mean, =239760/432 =555

Series of all even integers from 123 to 987 is an arithmetic progression. Hence the A.M of all elements of this series = first term + last term/2 . That is (124+986)/2=555

Between 124 and 986 are (986-124)/2 = 431 even numbers. You can write a finite arithmetic sum which is (431(124+986))/2 which gives us the sum of all those even numbers, 239,205. Then you divide that by the number of even numbers and get 555.

This is a arithmetic mean: 124+126+128......986. 124+(124+2)+(124+2*2)+......+986. a=124,d=2,n=481. Therefore,s=n/2[a+l] where l is the last number of the series. mean=s/n.This implies that mean=[a+l]/2. mean=[124+986]/2 =1110/2 =555.

124+987=1110 mean = 1110/2 = 555

Mean= sum of N numbers divided by N

even numbers from 123 to 987 is from 124 until 986. Sum=N(124+986)/2

Mean=(124+986)/2=1110/2=555

it is just (123+987)/2=555

_The Mean = Sum of the Integers / Numbers of the integer _

Then, Mean = $\frac{123+987}{2} = \frac{1110}{2} = 555$

The mean of all numbers is the same as the mean of only the even numbers. Since $123+987=1110$ , adding all numbers in between will give you some multiple of 1110. However, we are adding 2 numbers to get 1110, so to find the mean we divide by 2 to get $\boxed{555}$

There are 432 even numbers begining from 124 ending at 986 with a common differnece of 2..giving a sum of 239760.On dividing with 432 we get the answer as 555