Question : Find the average of even numbers from 8 to 1258
Correct Answer 633
Solution & Explanation
Solution
Method (1) to find the average of the even numbers from 8 to 1258
Shortcut Trick to find the average of the given continuous even numbers
The even numbers from 8 to 1258 are
8, 10, 12, . . . . 1258
After observing the above list of the even numbers from 8 to 1258 we find that the difference between two consecutive terms are equal. This means the list of the even numbers from 8 to 1258 form an Arithmetic Series.
In the Arithmetic Series of the even numbers from 8 to 1258
The First Term (a) = 8
The Common Difference (d) = 2
And the last term (ℓ) = 1258
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 1258
= 8 + 1258/2
= 1266/2 = 633
Thus, the average of the even numbers from 8 to 1258 = 633 Answer
Method (2) to find the average of the even numbers from 8 to 1258
Finding the average of given continuous even numbers after finding their sum
The even numbers from 8 to 1258 are
8, 10, 12, . . . . 1258
The even numbers from 8 to 1258 form an Arithmetic Series in which
The First Term (a) = 8
The Common Difference (d) = 2
And the last term (ℓ) = 1258
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 1258
1258 = 8 + (n – 1) × 2
⇒ 1258 = 8 + 2 n – 2
⇒ 1258 = 8 – 2 + 2 n
⇒ 1258 = 6 + 2 n
After transposing 6 to LHS
⇒ 1258 – 6 = 2 n
⇒ 1252 = 2 n
After rearranging the above expression
⇒ 2 n = 1252
After transposing 2 to RHS
⇒ n = 1252/2
⇒ n = 626
Thus, the number of terms of even numbers from 8 to 1258 = 626
This means 1258 is the 626th term.
Finding the sum of the given even numbers from 8 to 1258
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 1258
= 626/2 (8 + 1258)
= 626/2 × 1266
= 626 × 1266/2
= 792516/2 = 396258
Thus, the sum of all terms of the given even numbers from 8 to 1258 = 396258
And, the total number of terms = 626
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 1258
= 396258/626 = 633
Thus, the average of the given even numbers from 8 to 1258 = 633 Answer
Similar Questions
(1) Find the average of the first 2095 odd numbers.
(2) Find the average of odd numbers from 9 to 967
(3) Find the average of even numbers from 12 to 1406
(4) Find the average of odd numbers from 9 to 1381
(5) Find the average of odd numbers from 5 to 709
(6) Find the average of odd numbers from 5 to 1393
(7) Find the average of the first 2978 even numbers.
(8) Find the average of the first 538 odd numbers.
(9) What will be the average of the first 4183 odd numbers?
(10) Find the average of even numbers from 12 to 1952