For what value of 'm ' the points A ( m + 1 , 1 ) , B ( 2m + 1,3 ) and C ( 2m + 2 , 2m ) are collinear . 

The ratio of coins of 50 paisa, 25 paisa, and 10 paisa is 4:3:2. Find the total amount if the number of coins is 90.

The maximum number of common tangents drawn to two circles when both the circles touch each other externally is 

A does half as much work as B in one-third of the time taken by B. If together they take 10 days to complete a work, then the time take by B alone to do it would have been__

A boat moves downstream at the rate of 1 km in $$7{1\over 2}$$ minutes and upstream at the rate of 5 km an hour. What is the speed of the boat in the still water?  

The ratio of two numbers is 2: 3 and their L.C.M is 48.  What is the number?

$$ {{2^n+2^{n-1}}\over {2^{n+1} -2^n}}=?$$

A and  B can complete a work in 15 days and 10 days respectively. They started doing the work together but after 2 days B had to leave and A alone completed the remaining work. The whole work was completed in-