Question : Find the average of even numbers from 8 to 732
Correct Answer 370
Solution & Explanation
Solution
Method (1) to find the average of the even numbers from 8 to 732
Shortcut Trick to find the average of the given continuous even numbers
The even numbers from 8 to 732 are
8, 10, 12, . . . . 732
After observing the above list of the even numbers from 8 to 732 we find that the difference between two consecutive terms are equal. This means the list of the even numbers from 8 to 732 form an Arithmetic Series.
In the Arithmetic Series of the even numbers from 8 to 732
The First Term (a) = 8
The Common Difference (d) = 2
And the last term (ℓ) = 732
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 732
= 8 + 732/2
= 740/2 = 370
Thus, the average of the even numbers from 8 to 732 = 370 Answer
Method (2) to find the average of the even numbers from 8 to 732
Finding the average of given continuous even numbers after finding their sum
The even numbers from 8 to 732 are
8, 10, 12, . . . . 732
The even numbers from 8 to 732 form an Arithmetic Series in which
The First Term (a) = 8
The Common Difference (d) = 2
And the last term (ℓ) = 732
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 732
732 = 8 + (n – 1) × 2
⇒ 732 = 8 + 2 n – 2
⇒ 732 = 8 – 2 + 2 n
⇒ 732 = 6 + 2 n
After transposing 6 to LHS
⇒ 732 – 6 = 2 n
⇒ 726 = 2 n
After rearranging the above expression
⇒ 2 n = 726
After transposing 2 to RHS
⇒ n = 726/2
⇒ n = 363
Thus, the number of terms of even numbers from 8 to 732 = 363
This means 732 is the 363th term.
Finding the sum of the given even numbers from 8 to 732
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 732
= 363/2 (8 + 732)
= 363/2 × 740
= 363 × 740/2
= 268620/2 = 134310
Thus, the sum of all terms of the given even numbers from 8 to 732 = 134310
And, the total number of terms = 363
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 732
= 134310/363 = 370
Thus, the average of the given even numbers from 8 to 732 = 370 Answer
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