In a right triangle for an acute angle x, if sin x = $\frac{3}{7}$, then find the value of cosx.

In a class of 60 students, there are 35 boys. The average weight of boys is 42 kg and the average weight of the full class is 46.5 kg. Find the average weight of girls in the class.

The area of a sector of a circle is 110 cm² and the central angle of the sector is 56°, what is the radius of the circle? (Take π = 22/7)

If, in a competitive exam, the marks obtained by Sam are 19% less than those of Peter, then the marks obtained by Peter are how much percentage more than the marks obtained by Sam? (Correct to two decimal places)