Quantitative Aptitude - Arithmetic Ability Questions

Three solid spheres of radius 3 cm, 4 cm and 5 cm are melted and recasted into a solid sphere. What will be the percentage decrease in the surface area?

PQ is a diameter of a circle with centre O. RS is a chord parallel to PQ subtends an angle of 40° at the centre of the circle. If PR and QS are produced to meet at T, then what will be the measure (in degrees) of ∠PTQ?

If x stands for addition, / stands for subtraction, + stands for multiplication and - stands for division, then what is the value of 20 x 8 / 8 - 4 + 2 ?

In a class of 39 students there are 36 girls. The average weight of these girls is 38 Kg and average weight of the full class is 40 kgs. What is the average weight of the boys of the class?

Some masons promised to do a work in 10 days but 8 of them were absent and remaining did the work in 18 days. What was the original number of masons?

The sum of squares of three positive integers is 323. If the sum of squares of two numbers is twice the third, their product is

Pipes A, B, and C are attached to an empty cistern. While the first two can fill the cistern in 4 and 10 hours, respectively, the third can drain the cistern, when filled, in 6 hours. If all the three pipes are opened simultaneously when the cistern is three-fifth full, how many hours will be needed to fill the cistern?