CAT 2021 Slot 3 LRDI: Pure and Impure Solutions Answer Discussion

The set on pure and impure solutions had 4 questions: 2 TITA and 2MCQs. Can somebody share their answers? Thank you!


From what I remember, the answer to the first question that I marked was ‘10ml or more’. And I’ve seen others too claiming that to be the answer on Arun Sharma’s live chats. The only other question I answered was the 2nd question in the set which was a TITA. I marked ‘3’ just on a hunch. Tukka mara tha kyuki 4 ways for 4 bottles seemed too easy of an answer!
The first answer could be wrong, but it seems a lot of people agree on it.


I dont remember the first question and options. However, the options could be eliminated easily.

So far as the 2nd question is concerned . Number of P s to be declared to get through . The number of tests 2 be conducted i answered was 2. It cant be one because we dont know the impurity level of the one bottle which had impurity. If supposed it had 10 percent it wont get detected . However, if two tests with PP and PI were conducted since impurity level was 5 percent it got through the purity test. If the impurity level was above 10 percent it wouldcget detected in 2nd test and two more tests had to be conducted to get everything pass through. Which is the same case in question 3. The answer for 3rd question was 3 . PP can be the first test once get to know both are pure we can take either of the two and test with the rest two botles we will get the number of botles with impurity. Usingg the same logic i got the 3 as answer for question no 4 as well. The approach was u could either get the minimum and maximum number of tests using various combination of bottles. PP OR PI and Pwith P and I or woth I with p and p individually. I hope my approach was right.

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Can any tell me the answer for first question of the gant chart ptoblem. That abhi dhani wala . Fivr projects and five employees.
Was the first answer neither of the two

Hi for question 1 was there any option for only 10 ml. I markerked something for 10 ml. The other options i remeber were 1 ml , 100 ml and less than 10 ml. So far i remember . Was there any 10 ml opttion or it was 10 ml or more . Both the options cant be there logically 10 ml and 10 ml or more. The question was can be

There were two 5 ml solutions with one completely pure and one impure. How can the answer of impure be 10 ml or more than 10 ml when there’s a 5 ml solution that contains impurity?

I answered 1 guesss i remember. The question was wat can be the amount of impurity. The option i answered had no more or less than word to it i remember. What was the answer really. If impurity had to be detected which was 10 percent or more. Then it can be 1. Or something higher. I remeber i eliminated the options which diddnot fit to it. What were the answers for other three questions. I answered 2, 3 ,3. The last oje is wrong it was 4.

I had also attempted this set.
I had answered 10 ml or more for the 1st question.
For two TITA questions in which
For 1st we have to check wheather all 4 are pure or not I answered 1.
And for 2nd TITA I had answered 2.
For last mcq question I had answered 4.
Is these answers correct or not?

First 3 seem correct, I answered the same too.
1st. 10 ml or more
2nd. 1 trial was enough (if all 4 are P one)
3rd. tITA was 2
4th. 3 trials (if I understood the questions correctly). I believe the question was that out of the four solutions, 1 or 2 contain I (15% impurity in I) minimum number of trials to determine if 1 or 2 solutions contain I.

Answer was only(i)

So far i remember the employee month i got for ABCD was 9 8 9 9 and project months were 8 8 5 6 7. The total of project month should be one less than total employee month since there was one overlapping month. And there was question for that which two projects had same project month that 8 and 8. So far i remember.

I don’t remember the exact data but I believe question was quite simple. Many I’ve talked to marked the same. It is possible that my answer is wrong but less likely.

I don’t remember fully, that’s why I gave the disclaimer, but as far I know people are saying the '10ml or __ ’ option as the correct one.

That overlap was there for only some employees, not all.

Yes for two employees september month . The projects with project month of 8 and 8. I dont know know if my first answer is correct for which i marked neither of the two. The first condition was the employee month for all employees was same. For which i got 9 8 9 9. I reverifief the 8 month employee month again i got it 8 and for other 3 i got 9. I dont know if i went wrong somewhere

Are you sure this us correct, because I have the same answers


I considered the project month as 9, 9, 9, 8 for employees since there was a overlapping for Tinni.

But CAT answer key says otherwise. Is our assumption valid for questioning the CAT answer key.