The table shows the distribution of ages of 22 students in a school.

Using an assumed mean of 19, calculate, correct to three significant figures, the :

(a) mean age ; (b) standard deviation ; of the distribution.

The initial velocity of a particle of mass 0.1kg is 40 m/s in the direction of the unit vector j. The velocity of the particle changed to 30 m/s in the direction of the unit vector i. Find the change in momentum. 

A stone is dropped vertically downwards from the top of a tower of height 45m with a speed of 20 ms\(^{-1}\). Find the :

(a) time it takes to reach the ground ;

(b) speed with which it hits the ground. [Take \(g = 10 ms^{-2}\)].

(a) Differentiate \(\frac{x^{2} + 1}{(x + 1)^{2}}\) with respect to x.

(b)(i) Evaluate \(\begin{vmatrix} 1 & 2 & -1 \\ 2 & 3 & -1 \\ -1 & 1 & 3 \end{vmatrix}\).

(ii) Using the answer in (b)(i), solve the system of equations.

\(x + 2y - z = 4\)

\(2x + 3y - z = 2\)

\(-x + y + 3z = -1\).

(a) Using a scale of 2 cm to 30° on the x- axis, 2 cm to 0.2 units on the y- axis, on the same graph sheet, draw the graphs of \(y = \sin 2x\) and \(y = \cos x\) for \(0° \leq x \leq 210°\) at intervals of 30°.

(b) Using the graphs in (a), find the truth set of :

(i) \(\sin 2x = 0\) ; (ii) \(\sin 2x - \cos x = 0\).