Out of four consecutive numbers, the sum of the first two numbers is equal to the fourth number. What is half of the sum of the four numbers?

Correct option is D

Given:

Out of four consecutive numbers, the sum of the first two numbers is equal to the fourth number.

Solution:​

Let the four consecutive numbers be represented as:

n (the first number)

n + 1 (the second number)

n + 2 (the third number)

n + 3 (the fourth number)

Now, the sum of the first two numbers is equal to the fourth number. So:

n + (n + 1) = n + 3

2n + 1 = n + 3

2n − n = 3 − 1

n = 2

So, the four consecutive numbers are:  2, 3, 4, 5

Now, 

2 + 3 + 4 + 5 = 14

Half of the sum is: $$\frac{14}{2} = 7$$​

Thus, half of the sum of the four numbers is 7 .
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