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Question:     Find the average of even numbers from 6 to 1678


Correct Answer  842

Solution And Explanation

Solution

Method (1) to find the average of the even numbers from 6 to 1678

Shortcut Trick to find the average of the given continuous even numbers

The even numbers from 6 to 1678 are

6, 8, 10, . . . . 1678

After observing the above list of the even numbers from 6 to 1678 we find that the difference between two consecutive terms are equal. This means the list of the even numbers from 6 to 1678 form an Arithmetic Series.

In the Arithmetic Series of the even numbers from 6 to 1678

The First Term (a) = 6

The Common Difference (d) = 2

And the last term (ℓ) = 1678

The average of the numbers forming an Arithmetic Series

= The first term (a) + The last term (ℓ)/2

⇒ The average of numbers forming an Arithmetic Series = a + ℓ/2

Thus, the average of the even numbers from 6 to 1678

= 6 + 1678/2

= 1684/2 = 842

Thus, the average of the even numbers from 6 to 1678 = 842 Answer

Method (2) to find the average of the even numbers from 6 to 1678

Finding the average of given continuous even numbers after finding their sum

The even numbers from 6 to 1678 are

6, 8, 10, . . . . 1678

The even numbers from 6 to 1678 form an Arithmetic Series in which

The First Term (a) = 6

The Common Difference (d) = 2

And the last term (ℓ) = 1678

The Average of the given numbers

= Sum of the given numbers/Total number of given numbers

Thus, to find the average of the given numbers, first, we need to find their sum and the total number of given numbers

Finding the number of terms

For an Arithmetic Series, the nth term

an = a + (n – 1) d

Where

a = First term

d = Common difference

n = number of terms

an = nth term

Thus, for the given series of the even numbers from 6 to 1678

1678 = 6 + (n – 1) × 2

⇒ 1678 = 6 + 2 n – 2

⇒ 1678 = 6 – 2 + 2 n

⇒ 1678 = 4 + 2 n

After transposing 4 to LHS

⇒ 1678 – 4 = 2 n

⇒ 1674 = 2 n

After rearranging the above expression

⇒ 2 n = 1674

After transposing 2 to RHS

⇒ n = 1674/2

⇒ n = 837

Thus, the number of terms of even numbers from 6 to 1678 = 837

This means 1678 is the 837th term.

Finding the sum of the given even numbers from 6 to 1678

The sum of all terms (S) in an Arithmetic Series

= n/2 (a + ℓ)

Where, n = number of terms

a = First term

And, ℓ = Last term

Thus, the sum of all terms (S) of the given even numbers from 6 to 1678

= 837/2 (6 + 1678)

= 837/2 × 1684

= 837 × 1684/2

= 1409508/2 = 704754

Thus, the sum of all terms of the given even numbers from 6 to 1678 = 704754

And, the total number of terms = 837

Since, the average of the given numbers

= Sum of the given numbers/Total number of given numbers

Thus, the average of the given even numbers from 6 to 1678

= 704754/837 = 842

Thus, the average of the given even numbers from 6 to 1678 = 842 Answer


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