$$ ({2+\sqrt{5}})$$ and $$ ({2-\sqrt{5}})$$ is a quadratic equation with roots.

The average weight of A B and C is 50 kg . if the average weight of A and B be 48 kg and that of B and C be 45 kg , then find the weight of B ?

What is the quotient , when 2645 is divided by 48 ? 

A man earns a profit of 60% when he sells an article at 4/3 of the original selling price. Find the percent profit he makes at original price.

The average weight of three men is increased by 4 kg when one of them, whose weight is 100 kg, is replaced by another man. What is the weight of the new man? 

Simplify the following

  $${\sqrt { 10+{\sqrt { 25+ {\sqrt { 108 +\sqrt { 154+ \sqrt { 225} \ } \ } \ }} \ } } \ }\over \sqrt { 16+ 19.25×4^2} $$

Directions: Study the following pie chart carefully and answer the questions given beside.
The following pie chart gives the information about breakup of six different categories of workers in a company.

The number of Category B workers is what percentage more than that of category D workers?

The average marks obtained in a class of 50 students is 70%. The average of first 25 is 60% and that of 24 is 80%. What is the marks obtained by the last student?