Quantitative Ap...

Najib and Adil together can do a piece of work in 4 days. Adil and Eoin together can do the same work in 6 days. Najib and Adil together worked for 2 days and then Eoin did the work alone for 3 days. After that Eoin left and Najib and Adil together completed the rest of the work in 1 day. In how many days could all the three together have completed the whole work?

Mistry can fill a large tank from a river using a bucket in 60 minutes. Saha is 25% more efficient than Mistry and Datta is 20% more efficient than Saha. Mistry and Saha are allotted for filling up the tank. Datta, being a wicked kid, starts emptying the tank. Assuming filling the tank requires equal time and effort as that for emptying, what is the time required to fill the tank?

If a, b, c are in GP and log_ca, log_bc, log_ab, are in AP, then the common difference of AP is

From a collection of 12 bulbs of which 6 are defective 3 bulbs are chosen at random for three sockets in a room. Find the probability that the room is lighted if one bulb is sufficient to light the room.

A man borrows a certain sum of money and pays it back in 2 yrs in two equal installments. If C.I. is reckoned at 5% per annum and he pays back annually Rs. 441, what sum did he borrow?

If M is the mid-point of QR, find the length of QR.

The sum of the areas of two circles which touch each other externally is 153π. If the sum of their radii is 15, find the ratio of the larger to the smaller radius

A merchant bought some goods at a discount of 20% of the list price. He wants to mark them at such a price that he can give a discount of 20% of the marked price and still make a profit of 20% of the selling price. The per cent of the list price of which he should mark them is:

Find the orthocenter of the triangle formed by the points (0,0), (8,0) and (4,6).