Average
MCQs Math


Question:     What is the average of the first 1731 even numbers?


Correct Answer  1732

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 the given numbers

The first 1731 even numbers are

2, 4, 6, 8, . . . . 1731 th terms

Calculation of the sum of the first 1731 even numbers

We can find the sum of the first 1731 even 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 1731 even 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 the first 1731 even number,

n = 1731, a = 2, and d = 2

Thus, sum of the first 1731 even numbers

S1731 = 1731/2 [2 × 2 + (1731 – 1) 2]

= 1731/2 [4 + 1730 × 2]

= 1731/2 [4 + 3460]

= 1731/2 × 3464

= 1731/2 × 3464 1732

= 1731 × 1732 = 2998092

⇒ The sum of the first 1731 even numbers (S1731) = 2998092

Shortcut Method to find the sum of the first n even numbers

Thus, the sum of the first n even numbers = n2 + n

Thus, the sum of the first 1731 even numbers

= 17312 + 1731

= 2996361 + 1731 = 2998092

⇒ The sum of the first 1731 even numbers = 2998092

Calculation of the Average of the first 1731 even numbers

Formula to find the Average

Average = Sum of the given numbers/Number of the numbers

Thus, The average of the first 1731 even numbers

= Sum of the first 1731 even numbers/1731

= 2998092/1731 = 1732

Thus, the average of the first 1731 even numbers = 1732 Answer

Shortcut Trick to find the Average of the first n even numbers

(1) The average of the first 2 even numbers

= 2 + 4/2

= 6/2 = 3

Thus, the average of the first 2 even numbers = 3

(2) The average of the first 3 even numbers

= 2 + 4 + 6/3

= 12/3 = 4

Thus, the average of the first 3 even numbers = 4

(3) The average of the first 4 even numbers

= 2 + 4 + 6 + 8/4

= 20/4 = 5

Thus, the average of the first 4 even numbers = 5

(4) The average of the first 5 even numbers

= 2 + 4 + 6 + 8 + 10/5

= 30/5 = 6

Thus, the average of the first 5 even numbers = 6

Thus, the Average of the First n even numbers = n + 1

Thus, the average of the first 1731 even numbers = 1731 + 1 = 1732

Thus, the average of the first 1731 even numbers = 1732 Answer


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(3) Find the average of the first 293 odd numbers.

(4) Find the average of the first 4635 even numbers.

(5) What is the average of the first 185 even numbers?

(6) Find the average of even numbers from 8 to 562

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