Question

1. If the mean of x, x+2. x + 4, x + 6 and x + 8 is 11, what is the average of the last
three numbers?
(1) 11
(2) 13 (3) 14 (4) 15​

Answer 1

x+x+2+x+4+x+6+x+8/5=11

x+x+2+x+4+x+6+x+8=55

5x+20=55

5x=55–20

5x=35

x=35/5

x=7

If we have to calculate the average if last 3 numbers, then first we should know what the last 3 numbers are:

Substitute x=7 and get the numbers.

Third number is x+4. Therefore, 7+4=11

Fourth number is x+6. Therefore, 7+6=13

Fifth number is x+8. Therefore, 7+8=15

Average of last 3 numbers=11+13+15/3 =39/3=13

Average is 13

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Answer 2

Answer:

(2)13

Step-by-step explanation:

x, x+2,x+4,x+6,x+8

Mean-11

Mean=x+x+2+x+4+x+6+x+8/5

=>11=5x+20/5

=>11*5=5x+20

=>55-20=5x

=>35=5x

=>x=35/5

=>x=7

Now,

x+4=7+4=11

x+6=7+6=13

x+8=7+8=15

Avg.= 11+13+15/3

= 39/3

= 13

So, ans is 13