Presentation of information of variables which is arranged over a period of time (e.g., years, months, weeks etc.) on a graph paper is known as “time series graphs”.

The frequency distribution summarises the raw data by-making it concise and comprehensible. However, it does not show the details that are found in raw data and leads to loss of information. When the raw data is grouped into classes, an individual observation has no significance in further statistical calculations.
For example, suppose class 20-30 contains 6 ob-servations : 25, 25, 20, 22, 25 and-28. Such data is grouped as a class 20-30, then ^dividual values have no significance and only frequency, i.e. 6 is recorded and not their actual values.
All values in this class are assumed tofbe equal to the middle value of the class interval or class mark. Statistical calculations are based only on the value of class mark instead of the actual values

(i) Supply of skilled labour (like IT Engineers) has increased in India which means there is increase in resources(workforce)  and this causes a rightward shift in the Production Possibility curve.

(ii) Discovery of oil reserves in the gulf countries has caused a substantial increase in resources and hence the PPC shifts to the right .

Difference between classification and Tabulation

Table depicts the few differences between classification and tabulation

Only a point that lies on the budget line can be the equilibrium point because of the fact that only the combination of goods as represented by these points is affordable by the consumer given his income. On the other hand, the points that lie above the budget line are not affordable by the consumer, thereby, cannot be the equilibrium. In contrast to this, consumption bundles that lie below the budget line leave the consumer with some unspent income. This suggests that the consumer can have more of at least one of the goods and no less of the other. Thus, only a point on the budget line can be the equilibrium point for a consumer.

Allocation of resources means allocating the scarce resources in such a way that maximum wants of the society are fulfilled.  The following are related to the problem of allocating resources.
(a) what to produce and in what quantity?
(b) How to produce?

Old Price (P) = Rs 10
New Price = Rs 12
Change in Price ({tex}\Delta{/tex}P) = Rs 2( 12 - 10)
Percentage Change in Price
{tex}= \frac { \text { Change in Price } } { \text { Old Price } } \times 100{/tex}
{tex}= \frac { 2 } { 10 } \times 100 = 20 \%{/tex}
Percentage change in quantity demanded = -20% ( since the quantity demand has fallen by 20%)
(given)
We know that, Elasticity of Demand
E_d = - {tex}\frac { \text { Percentage Change in Quantity Demanded } } { \text { Percentage Change in Price}}{/tex}
= (-){tex}\frac { 20 } { 20 } ={/tex}(-)1
Now according to the given condition,
Old Price (P) = Rs 10
New Price = Rs 13 .
{tex}\therefore{/tex}Change in price = Rs 3(13 - 10)
Percentage Change in Price
{tex}= \frac { \text { Change in Price } } { \text { Old Price } } \times 100{/tex}={tex}\frac { 3 } { 10 } \times 100{/tex}= 30%
Elasticity of Demand (E_d)
{tex}- 1 = \frac { \text { Percentage Change in Quantity Demanded } } { 30 }{/tex}
So, Percentage change in quantity demanded =30%

therefore, the quantity demanded will fall by 30% when price rises from Rs 10 to Rs13.

Contraction of demand

There is contraction of demand for a commodity when there is increase in the price of commodity. When price is 10 dollars per kilogram the demand is 40 kilograms. When price increases to 20 dollars there is contraction of demand from 40 to 30 kilograms.

The diagram shows contraction of demand. Quality of demand is shown on OX axis. The price is shown on OY axis. DD is demand curve. When price increases the quantity demanded comes down and demand curve moves upward.

Market demand means the total quantity of a commodity that all its buyers are willing to purchase at different prices over a given period of time.
Factors determining market demand are:
(i) Own price of the good
(ii) Price of related goods
(iii) Income of the consumer
(iv) Taste and preferences of the consumer
(v) Expectation of the consumer regarding availability of a good
(vi) Size of population
(vii) Distribution of income
(viii) Composition of population