Question:
Find the average of odd numbers from 15 to 1313
Correct Answer
664
Solution And Explanation
Solution
Method (1) to find the average of the odd numbers from 15 to 1313
Shortcut Trick to find the average of the given continuous odd numbers
The odd numbers from 15 to 1313 are
15, 17, 19, . . . . 1313
After observing the above list of the odd numbers from 15 to 1313 we find that the difference between two consecutive terms are equal. This means the list of the odd numbers from 15 to 1313 form an Arithmetic Series.
In the Arithmetic Series of the odd numbers from 15 to 1313
The First Term (a) = 15
The Common Difference (d) = 2
And the last term (ℓ) = 1313
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 odd numbers from 15 to 1313
= 15 + 1313/2
= 1328/2 = 664
Thus, the average of the odd numbers from 15 to 1313 = 664 Answer
Method (2) to find the average of the odd numbers from 15 to 1313
Finding the average of given continuous odd numbers after finding their sum
The odd numbers from 15 to 1313 are
15, 17, 19, . . . . 1313
The odd numbers from 15 to 1313 form an Arithmetic Series in which
The First Term (a) = 15
The Common Difference (d) = 2
And the last term (ℓ) = 1313
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 odd numbers from 15 to 1313
1313 = 15 + (n – 1) × 2
⇒ 1313 = 15 + 2 n – 2
⇒ 1313 = 15 – 2 + 2 n
⇒ 1313 = 13 + 2 n
After transposing 13 to LHS
⇒ 1313 – 13 = 2 n
⇒ 1300 = 2 n
After rearranging the above expression
⇒ 2 n = 1300
After transposing 2 to RHS
⇒ n = 1300/2
⇒ n = 650
Thus, the number of terms of odd numbers from 15 to 1313 = 650
This means 1313 is the 650th term.
Finding the sum of the given odd numbers from 15 to 1313
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 odd numbers from 15 to 1313
= 650/2 (15 + 1313)
= 650/2 × 1328
= 650 × 1328/2
= 863200/2 = 431600
Thus, the sum of all terms of the given odd numbers from 15 to 1313 = 431600
And, the total number of terms = 650
Since, the average of the given numbers
= Sum of the given numbers/Total number of given numbers
Thus, the average of the given odd numbers from 15 to 1313
= 431600/650 = 664
Thus, the average of the given odd numbers from 15 to 1313 = 664 Answer
Similar Questions
(1) Find the average of odd numbers from 5 to 911
(2) Find the average of odd numbers from 15 to 707
(3) Find the average of the first 2469 even numbers.
(4) Find the average of odd numbers from 9 to 1167
(5) Find the average of odd numbers from 13 to 699
(6) Find the average of the first 2779 odd numbers.
(7) What is the average of the first 1190 even numbers?
(8) Find the average of odd numbers from 9 to 177
(9) Find the average of the first 3320 even numbers.
(10) Find the average of even numbers from 8 to 586