Question : Find the average of even numbers from 12 to 1864
Correct Answer 938
Solution & Explanation
Solution
Method (1) to find the average of the even numbers from 12 to 1864
Shortcut Trick to find the average of the given continuous even numbers
The even numbers from 12 to 1864 are
12, 14, 16, . . . . 1864
After observing the above list of the even numbers from 12 to 1864 we find that the difference between two consecutive terms are equal. This means the list of the even numbers from 12 to 1864 form an Arithmetic Series.
In the Arithmetic Series of the even numbers from 12 to 1864
The First Term (a) = 12
The Common Difference (d) = 2
And the last term (ℓ) = 1864
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 12 to 1864
= 12 + 1864/2
= 1876/2 = 938
Thus, the average of the even numbers from 12 to 1864 = 938 Answer
Method (2) to find the average of the even numbers from 12 to 1864
Finding the average of given continuous even numbers after finding their sum
The even numbers from 12 to 1864 are
12, 14, 16, . . . . 1864
The even numbers from 12 to 1864 form an Arithmetic Series in which
The First Term (a) = 12
The Common Difference (d) = 2
And the last term (ℓ) = 1864
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 12 to 1864
1864 = 12 + (n – 1) × 2
⇒ 1864 = 12 + 2 n – 2
⇒ 1864 = 12 – 2 + 2 n
⇒ 1864 = 10 + 2 n
After transposing 10 to LHS
⇒ 1864 – 10 = 2 n
⇒ 1854 = 2 n
After rearranging the above expression
⇒ 2 n = 1854
After transposing 2 to RHS
⇒ n = 1854/2
⇒ n = 927
Thus, the number of terms of even numbers from 12 to 1864 = 927
This means 1864 is the 927th term.
Finding the sum of the given even numbers from 12 to 1864
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 12 to 1864
= 927/2 (12 + 1864)
= 927/2 × 1876
= 927 × 1876/2
= 1739052/2 = 869526
Thus, the sum of all terms of the given even numbers from 12 to 1864 = 869526
And, the total number of terms = 927
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 12 to 1864
= 869526/927 = 938
Thus, the average of the given even numbers from 12 to 1864 = 938 Answer
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