The Ajmer express can move at 45 km./hr. without its rake and the speed is diminished by a constant that varies as the square root of the number of wagons attached. If it is known that with 9 wagons, the speed is 30 km./hr., what is the greatest number of wagons with which the train can just move?

The largest natural number which exactly divides the product of any four consecutive natural numbers is

While selling an article, a shopkeeper gives a discount of 5%. If he gives a discount of 7%, he earns Rs.15 less as profit. The marked price of the article is -

On selling an article for Rs.240, a trader loss of 10%.In order to gain 10%, he must sell that article for -

The average of 8 readings is 24.3, out of which the average of the first two is 18.5 and that of next three is 21.2. If the sixth reading is 3 less than seventh and 8 less than eight, what is the sixth reading? 

The value of a machine depreciates at the rate of 10% per annum. It was purchased 3 years ago. If its present value is Rs.53071.20, the purchase price of the machine was:

$$ {x^{8}+4\over{x^{4}+2x^{2}+2}}$$ is equal to

If the length of a rectangle is increased by 10% and the area is unchanged, then how much percent does the breadth decrease?