Question : ( 3 of 10 ) What is the average of the first 890 even numbers?
(A) 11 19/46 days or 11.413 days(B) 22 19/46 days or 22.413 days
(C) 46 days
(D) 23 days
Correct Answer 891
Solution & 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 890 even numbers are
2, 4, 6, 8, . . . . 890 th terms
Calculation of the sum of the first 890 even numbers
We can find the sum of the first 890 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 890 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 890 even number,
n = 890, a = 2, and d = 2
Thus, sum of the first 890 even numbers
S890 = 890/2 [2 × 2 + (890 – 1) 2]
= 890/2 [4 + 889 × 2]
= 890/2 [4 + 1778]
= 890/2 × 1782
= 890/2 × 1782 891
= 890 × 891 = 792990
⇒ The sum of the first 890 even numbers (S890) = 792990
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 890 even numbers
= 8902 + 890
= 792100 + 890 = 792990
⇒ The sum of the first 890 even numbers = 792990
Calculation of the Average of the first 890 even numbers
Formula to find the Average
Average = Sum of the given numbers/Number of the numbers
Thus, The average of the first 890 even numbers
= Sum of the first 890 even numbers/890
= 792990/890 = 891
Thus, the average of the first 890 even numbers = 891 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 890 even numbers = 890 + 1 = 891
Thus, the average of the first 890 even numbers = 891 Answer
Similar Questions
(1) Find the average of the first 2751 odd numbers.
(2) Find the average of even numbers from 12 to 766
(3) Find the average of odd numbers from 13 to 1223
(4) Find the average of even numbers from 10 to 1254
(5) Find the average of odd numbers from 9 to 933
(6) Find the average of the first 3536 odd numbers.
(7) Find the average of the first 3860 even numbers.
(8) Find the average of the first 953 odd numbers.
(9) What is the average of the first 183 odd numbers?
(10) Find the average of odd numbers from 3 to 119