Question

In proportion the 1 , 2 and 4 terms are 51, 68 and 108 respectively . Find the 3 term​

Answer 1

Answer:

81

Step-by-step explanation:

Let say third number = x

As number are in proportion

so

51 : 68  ::  x : 108

=> 51/68  = x/108

=> (17 × 3)/(17 × 4) =  x/108

Cancelling 17

=> 3/4 = x/108

=> x = 108 × 3 / 4

=> x = 27 × 4 × 3 / 4

Cancelling 4

=> x = 27 × 3

=> x = 81

Third number = 81

Answer 2

$\underline{\underline{\bold{Question:}}}$

In proportion the 1st , 2nd and 4th terms are 51, 68 and 108 respectively . Find the 3th term​.

$\underline{\bold{Solution:}}\\\\\\\bold{\textsf{Let the 3rd term of thr proportion be x.}}\\\\\\\bold{So}\\\\\\\bold{51:68::x:108}\\\\\\\implies{\bold{\dfrac{51}{68}=\dfrac{x}{108}}}\\\\\\\implies{\bold{x=\dfrac{51{\times}108}{68}=81.}}\\\\\\\boxed{\boxed{\bold{3rd\:term=81.}}}$

$\underline{\bold{Important\:formula:}}$

$\bold{Mean\:proportion=\sqrt{ab} }$

$\bold{Third\:proportion=\dfrac{b^2}{a}.}$