Question:
Find the average of even numbers from 8 to 1402
Correct Answer
705
Solution And Explanation
Solution
Method (1) to find the average of the even numbers from 8 to 1402
Shortcut Trick to find the average of the given continuous even numbers
The even numbers from 8 to 1402 are
8, 10, 12, . . . . 1402
After observing the above list of the even numbers from 8 to 1402 we find that the difference between two consecutive terms are equal. This means the list of the even numbers from 8 to 1402 form an Arithmetic Series.
In the Arithmetic Series of the even numbers from 8 to 1402
The First Term (a) = 8
The Common Difference (d) = 2
And the last term (ℓ) = 1402
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 1402
= 8 + 1402/2
= 1410/2 = 705
Thus, the average of the even numbers from 8 to 1402 = 705 Answer
Method (2) to find the average of the even numbers from 8 to 1402
Finding the average of given continuous even numbers after finding their sum
The even numbers from 8 to 1402 are
8, 10, 12, . . . . 1402
The even numbers from 8 to 1402 form an Arithmetic Series in which
The First Term (a) = 8
The Common Difference (d) = 2
And the last term (ℓ) = 1402
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 1402
1402 = 8 + (n – 1) × 2
⇒ 1402 = 8 + 2 n – 2
⇒ 1402 = 8 – 2 + 2 n
⇒ 1402 = 6 + 2 n
After transposing 6 to LHS
⇒ 1402 – 6 = 2 n
⇒ 1396 = 2 n
After rearranging the above expression
⇒ 2 n = 1396
After transposing 2 to RHS
⇒ n = 1396/2
⇒ n = 698
Thus, the number of terms of even numbers from 8 to 1402 = 698
This means 1402 is the 698th term.
Finding the sum of the given even numbers from 8 to 1402
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 1402
= 698/2 (8 + 1402)
= 698/2 × 1410
= 698 × 1410/2
= 984180/2 = 492090
Thus, the sum of all terms of the given even numbers from 8 to 1402 = 492090
And, the total number of terms = 698
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 1402
= 492090/698 = 705
Thus, the average of the given even numbers from 8 to 1402 = 705 Answer
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