Quantitative Aptitude - Arithmetic Ability Questions

If the time increases by 7 years, then simple interest increases by Rs 8400 on a sum of Rs 6000. What is the rate (in percentage) of interest per annum?

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

The sum of ages of 4 children born at intervals of 4 years each is 60. What is the age of the youngest child?

If two successive discounts of 50% and 10% are offered, then what is the net discount (in %)?

Point Q(-2,b) is the midpoint of segment EF. Co-ordinates of E are (-7,-6) and F are (a,0). What is the value of a and b?

What is the value of (1 + cotA)2 + (1 -­ cotA)2?

If x = 313- 3-13, then 3x2 + 9xis equal to

The area of a circle is 616 sq.m. Find its diameter.