Question : Find the average of even numbers from 12 to 1530
Correct Answer 771
Solution & Explanation
Solution
Method (1) to find the average of the even numbers from 12 to 1530
Shortcut Trick to find the average of the given continuous even numbers
The even numbers from 12 to 1530 are
12, 14, 16, . . . . 1530
After observing the above list of the even numbers from 12 to 1530 we find that the difference between two consecutive terms are equal. This means the list of the even numbers from 12 to 1530 form an Arithmetic Series.
In the Arithmetic Series of the even numbers from 12 to 1530
The First Term (a) = 12
The Common Difference (d) = 2
And the last term (ℓ) = 1530
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 1530
= 12 + 1530/2
= 1542/2 = 771
Thus, the average of the even numbers from 12 to 1530 = 771 Answer
Method (2) to find the average of the even numbers from 12 to 1530
Finding the average of given continuous even numbers after finding their sum
The even numbers from 12 to 1530 are
12, 14, 16, . . . . 1530
The even numbers from 12 to 1530 form an Arithmetic Series in which
The First Term (a) = 12
The Common Difference (d) = 2
And the last term (ℓ) = 1530
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 1530
1530 = 12 + (n – 1) × 2
⇒ 1530 = 12 + 2 n – 2
⇒ 1530 = 12 – 2 + 2 n
⇒ 1530 = 10 + 2 n
After transposing 10 to LHS
⇒ 1530 – 10 = 2 n
⇒ 1520 = 2 n
After rearranging the above expression
⇒ 2 n = 1520
After transposing 2 to RHS
⇒ n = 1520/2
⇒ n = 760
Thus, the number of terms of even numbers from 12 to 1530 = 760
This means 1530 is the 760th term.
Finding the sum of the given even numbers from 12 to 1530
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 1530
= 760/2 (12 + 1530)
= 760/2 × 1542
= 760 × 1542/2
= 1171920/2 = 585960
Thus, the sum of all terms of the given even numbers from 12 to 1530 = 585960
And, the total number of terms = 760
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 1530
= 585960/760 = 771
Thus, the average of the given even numbers from 12 to 1530 = 771 Answer
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