Quantitative Aptitude - Arithmetic Ability Questions

If m+n=1, then the value of m3+n3+3mnis equal to

A batsman scores 87 runs in the 21st match of his career. His average runs per match increases by 2. What was his average before the 21st match.

A cistern has one inlet, L and one inlet, M. L takes 5 hours to fill the empty tank, when M is not open and M takes 8 hours to empty the full tank, if the tank is two fifth full, how much time will it take to fill the tank completely when both L and M are opened simultaneously? (in hours)

∆PQR is right angled at Q. If sinP = 12/13, then what is the value of tanR?

If each median of an equilateral triangle has a length of 12cm. Then what will be the value of in-radius (in cm) of the equilateral triangle?

If A's salary is 40% less than that of B, then how much percent is B's salary more than that of A?

The average marks of 18 students in an examination was 60. It was later found that the marks of one student had been wrongly entered as 63 instead of 36. The correct average is:

56/32 simplified value?