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MCQs Math


Question:     Find the average of even numbers from 6 to 1000


Correct Answer  503

Solution And Explanation

Solution

Method (1) to find the average of the even numbers from 6 to 1000

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

The even numbers from 6 to 1000 are

6, 8, 10, . . . . 1000

After observing the above list of the even numbers from 6 to 1000 we find that the difference between two consecutive terms are equal. This means the list of the even numbers from 6 to 1000 form an Arithmetic Series.

In the Arithmetic Series of the even numbers from 6 to 1000

The First Term (a) = 6

The Common Difference (d) = 2

And the last term (ℓ) = 1000

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 1000

= 6 + 1000/2

= 1006/2 = 503

Thus, the average of the even numbers from 6 to 1000 = 503 Answer

Method (2) to find the average of the even numbers from 6 to 1000

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

The even numbers from 6 to 1000 are

6, 8, 10, . . . . 1000

The even numbers from 6 to 1000 form an Arithmetic Series in which

The First Term (a) = 6

The Common Difference (d) = 2

And the last term (ℓ) = 1000

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 1000

1000 = 6 + (n – 1) × 2

⇒ 1000 = 6 + 2 n – 2

⇒ 1000 = 6 – 2 + 2 n

⇒ 1000 = 4 + 2 n

After transposing 4 to LHS

⇒ 1000 – 4 = 2 n

⇒ 996 = 2 n

After rearranging the above expression

⇒ 2 n = 996

After transposing 2 to RHS

⇒ n = 996/2

⇒ n = 498

Thus, the number of terms of even numbers from 6 to 1000 = 498

This means 1000 is the 498th term.

Finding the sum of the given even numbers from 6 to 1000

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 1000

= 498/2 (6 + 1000)

= 498/2 × 1006

= 498 × 1006/2

= 500988/2 = 250494

Thus, the sum of all terms of the given even numbers from 6 to 1000 = 250494

And, the total number of terms = 498

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 1000

= 250494/498 = 503

Thus, the average of the given even numbers from 6 to 1000 = 503 Answer


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(5) Find the average of the first 3106 even numbers.

(6) Find the average of the first 1071 odd numbers.

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