Question

A bank gives 10% simple interest on deposits made by Senior citizens.
Illustrate by a graph the relation between the deposit and the interest gained. Use the graph to compute
(i) The annual interest obtained for an investment of ₹450.
(ii) The amount a Senior citizen has to invest to get an annual simple interest of ₹80.

• A. ₹40 and ₹800
• B. ₹45 and ₹750
• C. ₹40 and ₹400
• D. ₹45 and ₹800

Answer 1

The correct option is D ₹45 and ₹800

Deposit	Interest
₹100	$\frac{100\times 1\times 10}{100}$ = ₹10
₹200	$\frac{200\times 1\times 10}{100}$ = ₹20
₹300	$\frac{300\times 1\times 10}{100}$ = ₹30
₹400	$\frac{400\times 1\times 10}{100}$ = ₹40
₹1000	$\frac{1000\times 1\times 10}{100}$ = ₹100

Using the formula for calculating the simple interest, the following table of values is prepared.

Deposit(in. ₹)	100	200	300	400	1000
Annual S.I. (in. ₹)	10	20	30	40	100

These are the points which are to be plotted in the graph sheet. Let us take the deposits along x-axis and annual simple interest along y-axis.
We choose the scale as follows:
Then we plot the points and draw the straight line.
From the graph we find:
(i) Corresponding to ₹450 on the x-axis, we get the interest as ₹45 on the y-axis.
(ii) Corresponding to ₹80 on the y-axis, we get the deposit as ₹800 on the x-axis.