Question : Find the average of even numbers from 10 to 1600
Correct Answer 805
Solution & Explanation
Solution
Method (1) to find the average of the even numbers from 10 to 1600
Shortcut Trick to find the average of the given continuous even numbers
The even numbers from 10 to 1600 are
10, 12, 14, . . . . 1600
After observing the above list of the even numbers from 10 to 1600 we find that the difference between two consecutive terms are equal. This means the list of the even numbers from 10 to 1600 form an Arithmetic Series.
In the Arithmetic Series of the even numbers from 10 to 1600
The First Term (a) = 10
The Common Difference (d) = 2
And the last term (ℓ) = 1600
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 1600
= 10 + 1600/2
= 1610/2 = 805
Thus, the average of the even numbers from 10 to 1600 = 805 Answer
Method (2) to find the average of the even numbers from 10 to 1600
Finding the average of given continuous even numbers after finding their sum
The even numbers from 10 to 1600 are
10, 12, 14, . . . . 1600
The even numbers from 10 to 1600 form an Arithmetic Series in which
The First Term (a) = 10
The Common Difference (d) = 2
And the last term (ℓ) = 1600
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 1600
1600 = 10 + (n – 1) × 2
⇒ 1600 = 10 + 2 n – 2
⇒ 1600 = 10 – 2 + 2 n
⇒ 1600 = 8 + 2 n
After transposing 8 to LHS
⇒ 1600 – 8 = 2 n
⇒ 1592 = 2 n
After rearranging the above expression
⇒ 2 n = 1592
After transposing 2 to RHS
⇒ n = 1592/2
⇒ n = 796
Thus, the number of terms of even numbers from 10 to 1600 = 796
This means 1600 is the 796th term.
Finding the sum of the given even numbers from 10 to 1600
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 1600
= 796/2 (10 + 1600)
= 796/2 × 1610
= 796 × 1610/2
= 1281560/2 = 640780
Thus, the sum of all terms of the given even numbers from 10 to 1600 = 640780
And, the total number of terms = 796
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 1600
= 640780/796 = 805
Thus, the average of the given even numbers from 10 to 1600 = 805 Answer
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