An amount of money at compound interest grows up to Rs. 3,840 in 4 years and up to Rs. 3,936 in 5 years. Find the rate of interest. 

Pipes P and Q can fill a tank in 18 and 27 minutes, respectively, whereas Pipe R can empty the full tank in 54 minutes.  P and Q were opened together for 6 minutes and then   closed and R was opened. The tank was emptied by R alone in :

If shopkeeper sold the mobile for Rs.15000 and then he gets some loss. If he sold the same mobile at Rs.19200 and then he gets profit is double of loss. Find the cost price of the mobile?

Excluding stoppages, the speed of a train is 120 kmph and including stoppage, it is 50 kmph. For how many minutes does the train stop per hour?

Two students appeared for an examination. One of them secured 20 marks more than the other and his marks were 55% of the sum of their marks. The marks obtained by them are : 

Directions : What should come in place of the question mark (?) in the following number series? 

474 459 429 369 249 ?

The bar graph shows the number of painting sold an art gallery in each month from January to June.

 How many paintings does it need to sell in July for the 7 month average to be 90?