Question:
Find the average of odd numbers from 15 to 1057
Correct Answer
536
Solution And Explanation
Solution
Method (1) to find the average of the odd numbers from 15 to 1057
Shortcut Trick to find the average of the given continuous odd numbers
The odd numbers from 15 to 1057 are
15, 17, 19, . . . . 1057
After observing the above list of the odd numbers from 15 to 1057 we find that the difference between two consecutive terms are equal. This means the list of the odd numbers from 15 to 1057 form an Arithmetic Series.
In the Arithmetic Series of the odd numbers from 15 to 1057
The First Term (a) = 15
The Common Difference (d) = 2
And the last term (ℓ) = 1057
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 1057
= 15 + 1057/2
= 1072/2 = 536
Thus, the average of the odd numbers from 15 to 1057 = 536 Answer
Method (2) to find the average of the odd numbers from 15 to 1057
Finding the average of given continuous odd numbers after finding their sum
The odd numbers from 15 to 1057 are
15, 17, 19, . . . . 1057
The odd numbers from 15 to 1057 form an Arithmetic Series in which
The First Term (a) = 15
The Common Difference (d) = 2
And the last term (ℓ) = 1057
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 1057
1057 = 15 + (n – 1) × 2
⇒ 1057 = 15 + 2 n – 2
⇒ 1057 = 15 – 2 + 2 n
⇒ 1057 = 13 + 2 n
After transposing 13 to LHS
⇒ 1057 – 13 = 2 n
⇒ 1044 = 2 n
After rearranging the above expression
⇒ 2 n = 1044
After transposing 2 to RHS
⇒ n = 1044/2
⇒ n = 522
Thus, the number of terms of odd numbers from 15 to 1057 = 522
This means 1057 is the 522th term.
Finding the sum of the given odd numbers from 15 to 1057
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 1057
= 522/2 (15 + 1057)
= 522/2 × 1072
= 522 × 1072/2
= 559584/2 = 279792
Thus, the sum of all terms of the given odd numbers from 15 to 1057 = 279792
And, the total number of terms = 522
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 1057
= 279792/522 = 536
Thus, the average of the given odd numbers from 15 to 1057 = 536 Answer
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