If  $$\sqrt{a}+\sqrt{b}=15 \ and \ (\sqrt{a}-\sqrt{b} )=3$$ then the value of $$\sqrt{ab/4} $$ is 

In a class of 50 students there are 27 girls. The average weight of these girls is 45 kg and average weight of the full class is 49.6 kgs. What is the average weight of the boys of the class?

 In a test consisting of 140 Questions, a candidate correctly answered 70% of the first 80 questions. What percentage of the remaining questions does the candidate need to correctly answer to score 60% in the test?

What is the LCM (least common multiple) of 57 and   93?

If a, b and c are in GP and a^1/x=b^1/y=c^1/z. The value of 2y is?

What is the L.C.M of 12, 23, 24?

The difference between the greatest and the least four-digit numbers that begins with 3 and ends with 5 is: 

The volume of the largest right circular cone that can be cut out of a cube of edge 14 cm.