Question : Find the average of odd numbers from 7 to 437
Correct Answer 222
Solution & Explanation
Solution
Method (1) to find the average of the odd numbers from 7 to 437
Shortcut Trick to find the average of the given continuous odd numbers
The odd numbers from 7 to 437 are
7, 9, 11, . . . . 437
After observing the above list of the odd numbers from 7 to 437 we find that the difference between two consecutive terms are equal. This means the list of the odd numbers from 7 to 437 form an Arithmetic Series.
In the Arithmetic Series of the odd numbers from 7 to 437
The First Term (a) = 7
The Common Difference (d) = 2
And the last term (ℓ) = 437
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 7 to 437
= 7 + 437/2
= 444/2 = 222
Thus, the average of the odd numbers from 7 to 437 = 222 Answer
Method (2) to find the average of the odd numbers from 7 to 437
Finding the average of given continuous odd numbers after finding their sum
The odd numbers from 7 to 437 are
7, 9, 11, . . . . 437
The odd numbers from 7 to 437 form an Arithmetic Series in which
The First Term (a) = 7
The Common Difference (d) = 2
And the last term (ℓ) = 437
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 7 to 437
437 = 7 + (n – 1) × 2
⇒ 437 = 7 + 2 n – 2
⇒ 437 = 7 – 2 + 2 n
⇒ 437 = 5 + 2 n
After transposing 5 to LHS
⇒ 437 – 5 = 2 n
⇒ 432 = 2 n
After rearranging the above expression
⇒ 2 n = 432
After transposing 2 to RHS
⇒ n = 432/2
⇒ n = 216
Thus, the number of terms of odd numbers from 7 to 437 = 216
This means 437 is the 216th term.
Finding the sum of the given odd numbers from 7 to 437
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 7 to 437
= 216/2 (7 + 437)
= 216/2 × 444
= 216 × 444/2
= 95904/2 = 47952
Thus, the sum of all terms of the given odd numbers from 7 to 437 = 47952
And, the total number of terms = 216
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 7 to 437
= 47952/216 = 222
Thus, the average of the given odd numbers from 7 to 437 = 222 Answer
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