Question

The average of 1,3,5,7,9,11,.....25 terms is
A. 125
B.625
C.25
D.50

Answer 1

Answer:

25

Step-by-step explanation:

The sequence is odd numbers of increasing length based on the common difference of 2.

therefore, number of terms between 1 to 25 odd numbers is 13 as the sequence is 1,3,5,7,9,11,13,15,17,19,21,23,25.

To calculate the average use the given formula:  

average = 1/2((2a)+(n-1)d)

where,

n = number of terms = 13

a = first term = 1

d = common difference = 2

average = 1/2((2a)+(n-1)d)  

             = 1/2 ((2*1) + (13-1)*2

             = 1/2 (2) + 12*2  

             = 1 + 24

             = 25

Therefore, the average of 1,3,5,7,9,11,.....25 terms is 25.

Answer 2

Answer:

The average of 1,3,5,7,9,11,.....25 terms is 25 option c

Step-by-step explanation:

This is an AP

where

a = 1

n = 25

d = 2

Sum of 25 terms

= (n/2)(a + a+ 24d)

= (25/2)(1 + 1 + 24*2)

= (25/2)(50)

= (25)(25)

Average = Sum/ number of terms

=> Average = (25)(25)/(25)

= 25

option C is right answer