Quantitative Aptitude - Arithmetic Ability Questions

Three solid spheres have their radii r1, r2 and r3. The spheres are melted to form a solid sphere of bigger radius. Then the radius of the new sphere is

Rehman goes on a trip on his motor-cycle and rides for 661 kms. If he rides for 8 hours at a speed of 31 km/hr, find at what speed he travels for the remaining 7 hours of the journey?

Atul can do a piece of work in 18 days, Aaravya is 50% more efficient than Atul. How much more time does Atul take than Aaravya to do the same piece of work?

The average of 9 observations was found to be 35. Later on, it was detected that an observation 81 was misread as 18. The correct average of the observations is

Three numbers are in the ratio of 3:5:10 and their LCM is 630. Find their HCF.

If x – y – √18 = –1 and x + y – 3√2 = 1, then what is the value of 12xy(x2 – y2)?

What is the value of Tan 45° - 1/√3 Sec 60°?

What is the value of sin ­-300°?