Quant (Concepts): DI - Tricks & Traps Bar Diagrams

Most of the time Bar Diagrams questions appear to be easy on face but  they may be  deceiving. Let us learn some typical example of bar diagram, and derive key take away points.

DIRECTIONS: The following graph gives the data about Foreign Equity Inflow (FEI) for the five countries for two years 97 and 98.FEI is taken as the ratio of foreign equity inflow to the country's GDP, which is expressed as a percentage in the following graph.

Question 1. The country with the highest percentage change in FEI in 1998 relative to its FEI in 1997, is

a. India                     b. China
c. Malaysia              d. Thailan

Solution: The basic mistake which the students do while solving this problem is just taking the difference between the figures given on the bar tops as these figures are in percentages. So, as per this the answer is China which has the maximum difference (5.96 – 4.8 = 1.16) but this is actually wrong as we need to find the percent change between the years 1997 to 1998 for the given countries.

Student can follow the book method by calculating the percent change for all the given countries and find the answer. Besides that a smarter approach can also be applied,  which is just basic visualization of the bars of two years for the countries given in the choices. We find that the bar for 1998 is less than half of 1997 in case of India, which means that the bar remaining for 1998 is less than even 50% of the bar for 1997, and no other country it is even close to this kind of a change. Hence, the answer is India in this case as the percentage decrease is more than 50%.

Question 2. Which country has maximum change in the FEI?

a. India                     b. China
c. Malaysia              d. Thailand      

Solution: In this question, you are only asked to identify the country with the maximum change and not the percent change. We can calculate this using the difference between the values given on the top of the bars. So, as per this, the answer is China which has the maximum difference i.e.(5.96 – 4.8) = 1.16.

In this question, you need to apply the basic concept of subtracting the values given. Essentially, this was the mistake which was committed while calculating the percentage change in question 1.

Question 3. Supposing in Thailand 20% of FEI in 1997 and 50% of FEI in 1998 goes to Education sector then find the ratio of the amounts allocated to Education in 1997 to 1998, assuming the GDPs of both of these years for Thailand to be same.

a.1 : 3                     b. 5 : 21
c. 6 : 11                  d. 7 : 25

Solution: Taking the data from the bar chart for Thailand it can be seen that in 1997, 5.09% of the GDP is FEI and 20% of this goes to the Education sector and in 1998, 5.82% of the GDP is FEI and its 50% goes to the Education sector. Now if you try to calculate it actually by the conventional method, it will take a lot of time and effort.

Now as you only want to find the ratio of the amount spent on Education sector in the 1997 and 1998, you can do approximation by taking 5.09% as 5% approx. for 1997 and 5.82% as 6% approx. for 1998. Now just calculate ratio as 5 × 20 × GDP : 6 × 50 × GDP = 100 : 300 = 1 : 3 approximately.

To conclude, you can notice that the questions which take long to solve by conventional method, can be solved smartly also by applying logical and calculation oriented tricks.