Line Graphs / Line Charts:
A point-to-point graph, also called a line graph, is a pictorial rendition of data in which specific values of a function are plotted as dots on a coordinate plane. Adjacent pairs of dots are connected by straight lines. In most point-to-point graphs, the independent variable is rendered along the horizontal axis with values increasing from left to right. The dependent variable is rendered along the vertical axis with values increasing from the bottom up.
The illustration is a point-to-point graph showing the temperature in degrees Celsius as a function of the local time in a fictitious town over the 24-hour period representing a hypothetical midsummer day. Temperature readings, accurate to the nearest degree, are taken at 0000 hours (midnight), 0300 hours (3:00 a.m.), 0600 hours (6:00 a.m.), 0900 hours (9:00 a.m.) and so on at 3-hour intervals until the following midnight. The results are plotted as points. Finally, each adjacent pair of points is connected by a solid, straight line segment.
Point-to-point graphs are commonly used for portraying functions in which time is the independent variable. A point-to-point graph may be superimposed on a bar graph in a specialized plot called a Pareto chart . Some point-to-point graphs allow plotting of functions having multiple dependent variables, positive/negative variables and multi-category variables.
The following Line chart gives the ratio of the amounts of imports by a Company to the amount of exports from that Company over the period from 1995 to 2001. Answer the following questions based on following Line graph.
In how many of the given years were the exports more than imports ?
Clearly the exports are more than the imports implies that the ratio of value of imports to exports in less than 1.
So years are 1995, 1996, 1997 and 2000. So these are four years
The imports were minimum proportionate to the exports of the Company in the year :
Clearly from the line graph we can judge it is minimum in year 1997.
If the imports of a company in 1996 was Rs. 272 crores, the exports from the company in 1996 was:
We are given with the ratio of imports and exports in the line graph.
Let the exports from the company in 1996 was x
272/x = 0.85
=> x = 272/0.85
=> x = 320
Note: Please not that we are given the ratio of imports to exports, so export will will in denominator .
What was the percentage increase in imports from 1997 to 1998 ?
For calculating the percentage we will need value of exports, imports etc. We are only given with the ratio. So data in Inadequate.
Note: Please note in charts questions, most probably it includes 1 or more than 1 questions which are percentage based. So please clear percentage questions before preparing it. Because this is very scoring section.
If the imports in 1998 was Rs. 250 crores and the total exports in years 1998 and 1999 together was Rs 500 crores, then the imports in 1999 was :
The Ratio of imports to exports for the years 1998 and 1999 are 1.25 and 1.40 respectively.
Let the exports in the year 1998 = Rs. x crores
Then,the exports in the year 1999 = (500-x) crores
=> 1.25 = 250/x [because 1.25 is 1998 ratio]
=> x = 250/1.25 = 200 crore
Thus the exports in the year 1999 were 500 - 200 = 300 crore
Let the imports in the year 1999 = Rs y crore, Then 1.40 = y/300
=> y = 1.40*300 = 420 crore