**Directions for questions no. (1-4):** The regular mathematics faculty could not teach because of being sick. As a stopgap arrangement, different visiting faculty taught different topics on 4 different days in a week. The scheduled time for class was 7:00 am with maximum permissible delay of 20 minutes. The monsoon made the city bus schedules erratic and therefore the classes started on different times on different days.

Mr. Darji didn’t teach on Friday. Simple interest was taught in the class that started at 7:20 am. Mr. Birla took the class on Thursday, but he didn’t teach Number system. The class on Tuesday started at 7:00am, but Mr. Darji didn’t teach it. Mr. Agrawal didn’t teach Inequality. Mr. Chaturvedi, who didn’t teach Function, taught a class that started five minutes later than the class featuring the teacher who taught Number system. The teacher in Saturday’s class taught Function. Thursday’s class didn’t start at 7:10 am. No two classes started at the same time.

**Question 1: **Number system was taught by:

A. Mr. Agrawal on Tuesday

B. Mr. Agrawal on Friday

C. Mr. Darji on Thursday

D. Mr. Darji on Tuesday

E. None of these

**Question 2: **The class on Thursday started at:

A. 7:05 am and topic was Inequality.

B. 7:20 am and topic was Simple interest.

C. 7:00 am and topic was Simple interest.

D. 7:10 am and topic was Simple interest.

E. 7:05 am and topic was Number system.

**Question 3. : **The option which gives the correct teacher-subject combination is:

A. Mr. Birla – Inequality

B. Mr. Chaturvedi – Simple interest

C. Mr. Birla – Function

D. Mr. Darji – Simple interest

E. Mr. Darji – Function

**Question 4: **The option which gives a possible correct class time – week day combination is:

A. Thursday – 7:10 am, Friday – 7:05 am, Saturday – 7:05 am

B. Thursday – 7:20 am, Friday – 7:15 am, Saturday – 7:20 am

C. Thursday – 7:05 am, Friday – 7:20 am, Saturday-7:10 am

D. Thursday – 7:10 am, Friday – 7:15 am, Saturday – 7:05 am

E. Thursday – 7:20 am, Friday – 7:05 am, Saturday-7:10 am

### Answers and Explanations

**Solution**:
For questions 1 to 4:
Since Mr. Darji didn’t teach on Tuesday and Friday, he must have taught on Saturday.
Mr. Chaturvedi taught on Friday because he taught on a day which started five minutes late and it cannot be Tuesday as on Tuesday class started at 7.00 a.m.
Now, Number system was neither taught by Mr. Birla nor by Mr. Chaturvedi so it was taught on Tuesday by Mr. Agrawal.
Hence, the class on Friday started at 7.05 a.m. and we get the complete table as:

**Answer 1: (A)**

**Answer 2: ****(B)**

**Answer 3: (E)**

**Answer 4: ****(E)**

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