(xii) 

Let  ……….(i)

   = 

   ……….(ii)

Now, from eq. (i), 

= =   ……….(iii)

Here  and 

Then 

= 

  = 

Since,  and  is approximately equal to  and  respectively.

 From eq. (ii),  

= 0.00462

Therefore, approximate value of  is 3 + 0.00462= 3.00462.

(xiv) 

Let  ……….(i)

     ……….(ii)

Now, from eq. (i), 

= 

Here,  and , then 

= 

Since,  and  is approximately equal to  and  respectively.

 From eq. (ii),

 = 

Therefore, approximately value of  is 8 – 0.096 = 7.904.