Question:
Find the average of odd numbers from 13 to 1371
Correct Answer
692
Solution And Explanation
Solution
Method (1) to find the average of the odd numbers from 13 to 1371
Shortcut Trick to find the average of the given continuous odd numbers
The odd numbers from 13 to 1371 are
13, 15, 17, . . . . 1371
After observing the above list of the odd numbers from 13 to 1371 we find that the difference between two consecutive terms are equal. This means the list of the odd numbers from 13 to 1371 form an Arithmetic Series.
In the Arithmetic Series of the odd numbers from 13 to 1371
The First Term (a) = 13
The Common Difference (d) = 2
And the last term (ℓ) = 1371
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 13 to 1371
= 13 + 1371/2
= 1384/2 = 692
Thus, the average of the odd numbers from 13 to 1371 = 692 Answer
Method (2) to find the average of the odd numbers from 13 to 1371
Finding the average of given continuous odd numbers after finding their sum
The odd numbers from 13 to 1371 are
13, 15, 17, . . . . 1371
The odd numbers from 13 to 1371 form an Arithmetic Series in which
The First Term (a) = 13
The Common Difference (d) = 2
And the last term (ℓ) = 1371
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 13 to 1371
1371 = 13 + (n – 1) × 2
⇒ 1371 = 13 + 2 n – 2
⇒ 1371 = 13 – 2 + 2 n
⇒ 1371 = 11 + 2 n
After transposing 11 to LHS
⇒ 1371 – 11 = 2 n
⇒ 1360 = 2 n
After rearranging the above expression
⇒ 2 n = 1360
After transposing 2 to RHS
⇒ n = 1360/2
⇒ n = 680
Thus, the number of terms of odd numbers from 13 to 1371 = 680
This means 1371 is the 680th term.
Finding the sum of the given odd numbers from 13 to 1371
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 13 to 1371
= 680/2 (13 + 1371)
= 680/2 × 1384
= 680 × 1384/2
= 941120/2 = 470560
Thus, the sum of all terms of the given odd numbers from 13 to 1371 = 470560
And, the total number of terms = 680
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 13 to 1371
= 470560/680 = 692
Thus, the average of the given odd numbers from 13 to 1371 = 692 Answer
Similar Questions
(1) Find the average of the first 1892 odd numbers.
(2) Find the average of the first 1278 odd numbers.
(3) Find the average of the first 1011 odd numbers.
(4) Find the average of the first 3573 even numbers.
(5) What will be the average of the first 4523 odd numbers?
(6) Find the average of odd numbers from 5 to 1475
(7) What is the average of the first 359 even numbers?
(8) What is the average of the first 1863 even numbers?
(9) Find the average of even numbers from 12 to 1968
(10) Find the average of even numbers from 10 to 108