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MCQs Math


Question:     Find the average of even numbers from 8 to 1024


Correct Answer  516

Solution And Explanation

Solution

Method (1) to find the average of the even numbers from 8 to 1024

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

The even numbers from 8 to 1024 are

8, 10, 12, . . . . 1024

After observing the above list of the even numbers from 8 to 1024 we find that the difference between two consecutive terms are equal. This means the list of the even numbers from 8 to 1024 form an Arithmetic Series.

In the Arithmetic Series of the even numbers from 8 to 1024

The First Term (a) = 8

The Common Difference (d) = 2

And the last term (ℓ) = 1024

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 8 to 1024

= 8 + 1024/2

= 1032/2 = 516

Thus, the average of the even numbers from 8 to 1024 = 516 Answer

Method (2) to find the average of the even numbers from 8 to 1024

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

The even numbers from 8 to 1024 are

8, 10, 12, . . . . 1024

The even numbers from 8 to 1024 form an Arithmetic Series in which

The First Term (a) = 8

The Common Difference (d) = 2

And the last term (ℓ) = 1024

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 8 to 1024

1024 = 8 + (n – 1) × 2

⇒ 1024 = 8 + 2 n – 2

⇒ 1024 = 8 – 2 + 2 n

⇒ 1024 = 6 + 2 n

After transposing 6 to LHS

⇒ 1024 – 6 = 2 n

⇒ 1018 = 2 n

After rearranging the above expression

⇒ 2 n = 1018

After transposing 2 to RHS

⇒ n = 1018/2

⇒ n = 509

Thus, the number of terms of even numbers from 8 to 1024 = 509

This means 1024 is the 509th term.

Finding the sum of the given even numbers from 8 to 1024

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 8 to 1024

= 509/2 (8 + 1024)

= 509/2 × 1032

= 509 × 1032/2

= 525288/2 = 262644

Thus, the sum of all terms of the given even numbers from 8 to 1024 = 262644

And, the total number of terms = 509

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 8 to 1024

= 262644/509 = 516

Thus, the average of the given even numbers from 8 to 1024 = 516 Answer


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