If the ratio of the cost price and the selling price of an article be 4:5, then the percentage of profit is:

To cover a certain distance with a speed of 60 km/hr, a train takes 15 hours. If it covers the same distance in 12 hours, what will be its speed?

A man bought 30 defective machines for Rs. 1000. He repaired and sold them @ Rs. 300 per machine. He got a profit of Rs. 150 per machine. How much did he spend on repairs?

The sum of 10 terms of the arithmetic series is 390. If the third term of the series is 19, find the first term.

What is the sum of the first 11 terms of an arithmetic progression if the first term is -31 and last term is 29?

An article was sold at Rs. 950 allowing 5% discount on the marked price. The marked price of the article is

What will be the percentage of increase in the area of a square when each of its sides is increased by 10%?

Average of two numbers is 8 and average of other three numbers is 3; the average of the five numbers is

Due to a price hike of 20%, 4 kg less sugar is available for ₹120. What is the initial price per kg of sugar?

If the arithmetic mean of a, b, c is \(\rm \frac M 3\) and  \(\rm \frac{1}{a} + \frac{1}{b} = -\frac{1}{c} \) , then the arithmetic mean of a ², b ², c ² is

A person saves Rs. 1000 more than he did the previous year. If he saves Rs. 2000 in the first year, in how many years will he save Rs. 170000?

How many natural numbers lie between 3 and 200 which are divisible by 7?

The arithmetic mean of 16 student's scores is 320. Find the sum of these scores.