Question:
Find the average of the first 439 odd numbers.
Correct Answer
439
Solution And Explanation
Explanation
Method to find the average
Step : (1) Find the sum of given numbers
Step: (2) Divide the sum of given number by the number of numbers. This will give the average of given numbers
The first 439 odd numbers are
1, 3, 5, 7, 9, . . . . 439 th terms
Calculation of the sum of the first 439 odd numbers
We can find the sum of the first 439 odd numbers by simply adding them, but this is a bit difficult. And if the list is long, it is very difficult to find their sum. So, in such a situation, we will use a formula to find the sum of given numbers that form a particular pattern.
Here, the list of the first 439 odd numbers forms an Arithmetic series
In an Arithmetic Series, the common difference is the same. This means the difference between two consecutive terms are same in an Arithmetic Series.
The sum of n terms of an Arithmetic Series
Sn = n/2 [2a + (n – 1) d]
Where, n = number of terms, a = first term, and d = common difference
In the series of first 439 odd number,
n = 439, a = 1, and d = 2
Thus, sum of the first 439 odd numbers
S439 = 439/2 [2 × 1 + (439 – 1) 2]
= 439/2 [2 + 438 × 2]
= 439/2 [2 + 876]
= 439/2 × 878
= 439/2 × 878 439
= 439 × 439 = 192721
⇒ The sum of first 439 odd numbers (Sn) = 192721
Shortcut Method to find the sum of first n odd numbers
Thus, the sum of first n odd numbers = n2
Thus, the sum of first 439 odd numbers
= 4392 = 192721
⇒ The sum of first 439 odd numbers = 192721
Calculation of the Average of the first 439 odd numbers
Formula to find the Average
Average = Sum of given numbers/Number of numbers
Thus, The average of the first 439 odd numbers
= Sum of first 439 odd numbers/439
= 192721/439 = 439
Thus, the average of the first 439 odd numbers = 439 Answer
Shortcut Trick to find the Average of the first n odd numbers
The average of the first 2 odd numbers
= 1 + 3/2
= 4/2 = 2
Thus, the average of the first 2 odd numbers = 2
The average of the first 3 odd numbers
= 1 + 3 + 5/3
= 9/3 = 3
Thus, the average of the first 3 odd numbers = 3
The average of the first 4 odd numbers
= 1 + 3 + 5 + 7/4
= 16/4 = 4
Thus, the average of the first 4 odd numbers = 4
The average of the first 5 odd numbers
= 1 + 3 + 5 + 7 + 9/5
= 25/5 = 5
Thus, the average of the first 5 odd numbers = 5
Thus, the Average of the the First n odd numbers = n
Thus, the average of the first 439 odd numbers = 439
Thus, the average of the first 439 odd numbers = 439 Answer
Similar Questions
(1) Find the average of odd numbers from 3 to 1199
(2) Find the average of odd numbers from 7 to 1429
(3) Find the average of even numbers from 4 to 1768
(4) Find the average of the first 3248 odd numbers.
(5) Find the average of the first 3172 even numbers.
(6) Find the average of the first 2403 odd numbers.
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