The average age of a class of 40 students and a teacher reduces by 0.5 years, if we exclude the teacher. If the initial average age is 18 years, then what is the age of the teacher?

A person has some amount with him. 25% of it is stolen in a bus, 10% is lost through a hole in the pocket, 50% of remainder is spent on food. He then purchases a book worth Rs. 26 from the remainder. He walks back home because all his money is over. What was the initial amount?

When a amount is given at a compound interest rate of 18% per annum, the interest received on compound annual payable in two years will be Rs 960 more than half yearly interest. What is the amount?

A runner starts running from a point at 6:00 am with a speed of 8km / hr. Another racer starts from the same point at 8:30 am in the same direction with a speed of 10km / hr. At what time of the day (in P.M.) will the second racer will overtake the other runner? 

On dividing a certain number by 342 we get 47 as remainder. If the same number is divided by 18, what will be the remainder?

Find the sum of all prime numbers between 10 and 90.

What is the minimum number of square marbles required to tile a floor of length 5 meters 78 cm. and width 3 meters 74 cm?