Question

Directions:- Study the following information carefully to answer the question given below.

Guest lectures on five subjects viz. Economics, History, Statistics, English and Mathematics have to be arranged in a week from Monday to Friday. Only one lecture can be arranged on each day. Economics cannot be scheduled on Tuesday. Guest faculty for History is available only on Tuesday. Mathematics lecture has to be scheduled immediately after the day of Economics lecture. English lecture has to be scheduled immediately before the day of the Economics lecture.

Which lecture is scheduled before the Mathematics lecture?

• A. Economics
• B. History
• C. Statistics
• D. English
• E. Inadequate data

Answer 1

The correct option is A Economics

Read carefully the given information and prepare a table. While preparing the table, keep the given information and options of the conditions in mind so that any error in the table can be avoided. Prepare the table considering two information - days and subjects as follow :
$\begin{array}{cccccc}Days/\to & Monday& Tuesday& Wednesday& Thursday& Friday\\ Subjects\downarrow & & & & & \\ Economics& & & & & \\ History& & & & & \\ Statistics& & & & & \\ English& & & & & \\ Mathematics& & & & & \end{array}$
Before filling the table think for a while again. Economics cannot be scheduled on Tuesday. It does not mean that Economics can be scheduled on any day other than Tuesday. Keep in mind that the most important condition in problem-solving is perceiving the problem in its totality. The condition says that the Mathematics lecture has to be delivered immediately after the day of Economics lecture and the English lecture has to be delivered immediately before the day of the Economics lecture. Clearly, Economics lecture cannot be scheduled either on Monday or on Friday because these two days cannot fulfil conditions of immediately before and after respectively. Immediately after Monday, Tuesday is reserved for History and immediately after Friday there is no schedule on Saturday and Sunday.
So Economics lecture can be scheduled only on Thursday. Now we can fill the above table as follows:
$\begin{array}{cccccc}Days/\to & Monday& Tuesday& Wednesday& Thursday& Friday\\ Subjects\downarrow & & & & & \\ Economics& X& X& X& ✓& X\\ History& X& ✓& X& X& X\\ Statistics& & & & & \\ English& X& X& ✓& X& X\\ Mathematics& X& X& X& X& ✓\end{array}$
It is easy to fill the table on the basis of the given information. History lecture is scheduled on Tuesday; Economics is on Thursday; Mathematics is on Friday and English is on Wednesday. The only day left is Monday that is the day for Statistics. The above table shows that all the days are engaged except Monday. Now, we can complete the table as follows :
$\begin{array}{cccccc}Days/\to & Monday& Tuesday& Wednesday& Thursday& Friday\\ Subjects\downarrow & & & & & \\ Economics& X& X& X& ✓& X\\ History& X& ✓& X& X& X\\ Statistics& ✓& X& X& X& X\\ English& X& X& ✓& X& X\\ Mathematics& X& X& X& X& ✓\end{array}$
Importance of 'x' sign in a table: "x" sign is like an alarm that alerts you against wasting your time in wrong area. 'x' means there is no space or option to consider over. You should spend your energy on blank spaces of the table. If there is no 'x' sign, you can get confused for a little bit. Have a glance upon the same table as shown above but without 'x'.
$\begin{array}{cccccc}Days/\to & Monday& Tuesday& Wednesday& Thursday& Friday\\ Subjects\downarrow & & & & & \\ Economics& & & & ✓& \\ History& & ✓& & & \\ Statistics& ✓& & & & \\ English& & & ✓& & \\ Mathematics& & & & & ✓\end{array}$
If the observations/data are more in number, 'x' will help you immensly. Now we can answer the questions of the given example on the basis of table:-

Economics lecture is scheduled befor Mathematics lecture.
Hence, required answer is (A).