A trust fund has $\mathrm{Rs} 30000$ that must be invested in two different types of bonds. The first bond pays $5\%$interest per year, and the second bond pays $7\%$interest per year. Using matrix multiplication, determine how to divide $\mathrm{Rs} 30000$ among the two types of bonds. If the trust fund must obtain an annual total interest of $\mathrm{Rs} 2000$.

To promote making of toilets for women, an organisation tried to generate awareness through $\left(\mathrm{i}\right)$ house calls, $\left(\mathrm{ii}\right)$letters, and $\left(\mathrm{iii}\right)$ announcements. The cost for each mode per attempt is given below:

$\left(\mathrm{i}\right)₹50$ $\left(\mathrm{ii}\right)₹20$ $\left(\mathrm{iii}\right)₹40$

The number of attempts made in three villages$X,Y$ and $Z$ are given below:
       $\left(\mathrm{i}\right) \left(\mathrm{ii}\right) \left(\mathrm{iii}\right)$
$X 400 300 100$
$Y 300 250 75$
$Z 500 400 150$

Find the total cost incurred by the organisation for three villages separately, using matrices.

In a parliament election, a political party hired a public relations firm to promote its candidates in three ways -telephone, house calls and letters. The cost per contact (in paisa) is given in matrix $A$ as

$A=\left[\begin{array}{c}140\\ 200\\ 150\end{array}\right]\begin{array}{c}\mathrm{Telephone}\\ \mathrm{House}calls\\ \mathrm{Letters}\end{array}$

The number of contacts of each type made in two cities $X$ and $Y$ is given in the matrix $B$ as

 $$\begin{gathered} \begin{array}{ccc}\mathrm{Telephone}& \mathrm{Housecall}& \mathrm{Letter}\end{array} \\ \mathrm{B}=\left[\begin{array}{lll} 1000& 500& 5000\\ 3000& 1000& 10000\end{array}\right] \begin{array}{c}\to \mathrm{City} \mathrm{X}\\ \to \mathrm{City} \mathrm{Y}\end{array} \end{gathered}$$

Find the total amount spent by the party in the two cities.

What should one consider before casting his/her vote - party's promotional activity of their social activities?