Quantitative Aptitude - Arithmetic Ability Questions

If a + b = ­ 8 and a2 + b2 = 34, then value of ab is

A, B and C can do a job working alone in 50, 75 and 20 days respectively. They all work together for 4 days, then C quits. How many days will A and B take to finish the rest of the job?

The average age of a class of 6 girls is x years. Four new girls having ages x – 2, x + 2, x + 4 and x + 6 joins the class. What is the new average age (in years) of the class?

If 15% of x is three times of 10% of y, then x:y = 

If the radius of a circle is decreased to 25% of its original value, calculate the percentage decrease in the area of the circle

The ratio of the cost price and selling price of a bulb is 15 : 18. What is the profit percentage?

The sum of the digits of a 2-digit number is 11. If we add 45 to the number, the new number obtained is a number formed by interchange of the digits. What is the number?

A cuboid has dimensions 8 cm x 10 cm x 12 cm. It is cut into small cubes of side 2 cm. What is the percentage increase in the total surface area?