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The sum of 6 consecutive even number is 126. what is the fourth number in the sequence

2 Answers

3 votes

Answer:

The answer is 22.

Explanation:

Hope this helps!

User Francesco Pegoraro
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2 votes

let's start off by keeping in mind that, if you multiply any integer by 2, regardless of what that integer is, you will always get an EVEN integer, say 13 * 2 = 26, or 18 * 2 = 36 and so on.

let' see a few consecutive even integers

2, 4, 6, 8, 10, 12 , 14..............

notice, to get another one from any of them, we can simply hop back or forwards twice, namely 8 ± 2, gives us 6 and 10.

so let's use for our first even integer say "2a".

that simply means our next even integer can just be 2a + 2

and we add 2 again and so on to get all 6 even integers.

now, we know they add sum up to 126.



\bf \stackrel{1st}{(2a)}+\stackrel{2nd}{(2a+2)}+\stackrel{3rd}{(2a+4)}+\stackrel{4th}{(2a+6)}+\stackrel{5th}{(2a+8)}+\stackrel{6th}{(2a+10)}~~=~~126 \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ 12a+30=126\implies 12a=96\implies a=\cfrac{96}{12}\implies \boxed{a=8} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ \stackrel{4th}{2(8)+6}\implies 22

User KayakDave
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