A boat goes downstream through certain distance in 1 hour and returns back in 1.5 hours. If the current is flowing at the speed of 3 km/hr, what is the speed of the boat in still water?

How much water should be added to 30 litre solution of water and alcohol containing 90% alcohol so as to reduce the content of alcohol to 80%?

Two successive discounts of 30% followed by 25% are equivalent to a single discount of which of the following?

Out of 100 students, 50 failed in English and 30 failed in Maths. If 12 students failed in both English and Maths, how many passed in both the subjects?

Mukesh scored 21 runs more than Girish in a cricket match. If the sum of the runs scored by both of them together is 237, what are the runs scored by Girish?

If 200% of a number is 800, what will be 0.5% of that number?

"B" is 10% heavier than "A" and "C" is 10% lighter than "B". Which of the following statements is TRUE?

The average of six numbers is 3.95. If the average of two of them is 3.4 while that of the other two is 3.85, what is the average of the remaining two numbers?

Which of the following numbers does not fit in the following series? 4, 8, 20, 48, 144, 288, 864