Question

if 4,a,b,28 are in arithemetic progression then the value of b is A. 20. B.19. C. 23. D. 12.

Answer 1

Given : 4,a,b,28 are in arithmetic progression

To Find :

the value of b  

A. 20. B.19. C. 23. D. 12.

Solution:

4,a,b,28 are in arithmetic progression

=> a - 4  = b - a  =  28 - b   = common difference

a - 4  = 28  -  b

=> a + b  = 32

a - 4  = b - a  

=> 2a = b + 4

=> 2a - b  = 4

 a + b  = 32  

2a - b =  4

=> 3a = 36

=> a = 12

b = 20

Value of b =  20

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Answer 2

$\underline{\textbf{Given:}}$

$\textsf{4, a, b, 28 are in A.P}$

$\underline{\textbf{To find:}}$

$\textsf{The value of b}$

$\underline{\textbf{Solution:}}$

$\textsf{Let 'd' be the common difference of the given A.P}$

$\mathsf{Then,}$

$\mathsf{a=4+d}$

$\mathsf{b=4+2d}$

$\mathsf{28=4+3d}$

$\implies\mathsf{3d=28-4}$

$\implies\mathsf{3d=24}$

$\implies\mathsf{d=8}$

$\mathsf{a=4+d=4+8=12}$

$\mathsf{b=4+2d=4+2(8)=4+16=20}$

$\underline{\textbf{Answer:}}$

$\textbf{The value of b is 20}$

$\underline{\textbf{Find more:}}$

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