Question:
Find the average of even numbers from 10 to 226
Correct Answer
118
Solution And Explanation
Solution
Method (1) to find the average of the even numbers from 10 to 226
Shortcut Trick to find the average of the given continuous even numbers
The even numbers from 10 to 226 are
10, 12, 14, . . . . 226
After observing the above list of the even numbers from 10 to 226 we find that the difference between two consecutive terms are equal. This means the list of the even numbers from 10 to 226 form an Arithmetic Series.
In the Arithmetic Series of the even numbers from 10 to 226
The First Term (a) = 10
The Common Difference (d) = 2
And the last term (ℓ) = 226
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 10 to 226
= 10 + 226/2
= 236/2 = 118
Thus, the average of the even numbers from 10 to 226 = 118 Answer
Method (2) to find the average of the even numbers from 10 to 226
Finding the average of given continuous even numbers after finding their sum
The even numbers from 10 to 226 are
10, 12, 14, . . . . 226
The even numbers from 10 to 226 form an Arithmetic Series in which
The First Term (a) = 10
The Common Difference (d) = 2
And the last term (ℓ) = 226
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 10 to 226
226 = 10 + (n – 1) × 2
⇒ 226 = 10 + 2 n – 2
⇒ 226 = 10 – 2 + 2 n
⇒ 226 = 8 + 2 n
After transposing 8 to LHS
⇒ 226 – 8 = 2 n
⇒ 218 = 2 n
After rearranging the above expression
⇒ 2 n = 218
After transposing 2 to RHS
⇒ n = 218/2
⇒ n = 109
Thus, the number of terms of even numbers from 10 to 226 = 109
This means 226 is the 109th term.
Finding the sum of the given even numbers from 10 to 226
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 10 to 226
= 109/2 (10 + 226)
= 109/2 × 236
= 109 × 236/2
= 25724/2 = 12862
Thus, the sum of all terms of the given even numbers from 10 to 226 = 12862
And, the total number of terms = 109
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 10 to 226
= 12862/109 = 118
Thus, the average of the given even numbers from 10 to 226 = 118 Answer
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