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Question:     Find the average of even numbers from 10 to 1544


Correct Answer  777

Solution And Explanation

Solution

Method (1) to find the average of the even numbers from 10 to 1544

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

The even numbers from 10 to 1544 are

10, 12, 14, . . . . 1544

After observing the above list of the even numbers from 10 to 1544 we find that the difference between two consecutive terms are equal. This means the list of the even numbers from 10 to 1544 form an Arithmetic Series.

In the Arithmetic Series of the even numbers from 10 to 1544

The First Term (a) = 10

The Common Difference (d) = 2

And the last term (ℓ) = 1544

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 10 to 1544

= 10 + 1544/2

= 1554/2 = 777

Thus, the average of the even numbers from 10 to 1544 = 777 Answer

Method (2) to find the average of the even numbers from 10 to 1544

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

The even numbers from 10 to 1544 are

10, 12, 14, . . . . 1544

The even numbers from 10 to 1544 form an Arithmetic Series in which

The First Term (a) = 10

The Common Difference (d) = 2

And the last term (ℓ) = 1544

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 10 to 1544

1544 = 10 + (n – 1) × 2

⇒ 1544 = 10 + 2 n – 2

⇒ 1544 = 10 – 2 + 2 n

⇒ 1544 = 8 + 2 n

After transposing 8 to LHS

⇒ 1544 – 8 = 2 n

⇒ 1536 = 2 n

After rearranging the above expression

⇒ 2 n = 1536

After transposing 2 to RHS

⇒ n = 1536/2

⇒ n = 768

Thus, the number of terms of even numbers from 10 to 1544 = 768

This means 1544 is the 768th term.

Finding the sum of the given even numbers from 10 to 1544

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 10 to 1544

= 768/2 (10 + 1544)

= 768/2 × 1554

= 768 × 1554/2

= 1193472/2 = 596736

Thus, the sum of all terms of the given even numbers from 10 to 1544 = 596736

And, the total number of terms = 768

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 10 to 1544

= 596736/768 = 777

Thus, the average of the given even numbers from 10 to 1544 = 777 Answer


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