r/CMI

▲ 3 r/CMI

CMI MSc DS Incorrect Solution in Answer key (Part A, Q6)

Objection to Answer Key: Part (A), Question 6

CMI M.Sc. Data Science Entrance Examination 2026


The Question

A box contains 3 red balls and 2 blue balls. Two balls are drawn one after another without replacement. Let A be the event that both balls are red, and B the event that the first ball is red. Which of the following are true?

  • (a) P(A) = 3/10
  • (b) P(B) = 3/5
  • (c) P(Bᶜ | Aᶜ) = 2/3 (here Xᶜ is the event that X does not take place)
  • (d) P(A | B) = 3/5

Official Key Answer: (a), (b), (c)
Correct Answer: (a), (b)


Correction for Option (c)

The official solution states: "Note that Aᶜ = {RB, BB, BR} so there are exactly two possibilities for the first ball being blue. Hence c is true." However, this logic falsely assumes outcomes in Aᶜ to be equiprobable. Because sampling is performed without replacement, the exact probabilities for the constituent states are asymmetric:

P(RB) = 3/5 × 2/4 = 3/10
P(BR) = 2/5 × 3/4 = 3/10
P(BB) = 2/5 × 1/4 = 1/10

By definition, Bᶜ (the first ball is blue) is a strict subset of Aᶜ (not both balls are red), meaning Bᶜ ∩ Aᶜ = Bᶜ. Evaluating the conditional probability equation yields:

P(Aᶜ) = 1 - P(A) = 1 - 3/10 = 7/10
P(Bᶜ ∩ Aᶜ) = P(Bᶜ) = P(BR) + P(BB) = 3/10 + 1/10 = 4/10

P(Bᶜ | Aᶜ) = P(Bᶜ ∩ Aᶜ) / P(Aᶜ) = (4/10) / (7/10) = 4/7

Since 4/7 (≈ 0.5714) ≠ 2/3, option (c) is false.


Conclusion

The correct set of true statements is (a) and (b). I request the admissions committee to re-evaluate the scoring template for this question.

#Update: They've corrected it now

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u/Lead_balloon784 — 2 days ago
▲ 8 r/CMI

4 years Bs

Cmi now changed its course to 4 years Bs,does that mean people get eligible for Gate directly without doing masters there?

Also with the inclusion of data science will it increase employability?

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u/Connect_Excuse5178 — 2 days ago
▲ 1 r/CMI

What are you getting in CMI BSc Part A?

Today the draft solutions have been released. If you have checked the pdf, please comment how much you are getting in part A.

Many people are losing marks in Fill in the blanks.

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u/Kooky-Evening-4383 — 3 days ago
▲ 11 r/CMI

Profile of a successful student at CMI?

I wanted to understand what it realistically takes for a bachelor’s student at CMI to get into top universities abroad for masters/PhD in Math/CS (MIT/Stanford/Princeton-level places).

What kind of profile do successful students usually have?

How much research/project work did they do?

Were publications common?

How important were grades/rank?

Did most people do internships or REUs?

How strong do recommendation letters need to be?

Do professors/assnt. Professors give strong recommendation letters?

Also, how common is this path in practice at CMI?

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u/Electronic-Elk-4529 — 4 days ago
▲ 47 r/CMI+9 crossposts

Indian Education system ELIMINATES PEOPLE not SELECTS THEM

Hello everyone this is my first reddit post and i have to share this thing

From: [my email]

To: secy.moeducation@gov.in

Cc: secy.ugc@nic.in, chairman@aicte-india.org, js.seel@nic.in

Date: Jan 11, 2026, 12:53 PM

Subject: Formal Representation on NEP 2020 Implementation Gap in Computer Science

Education

Respected Sir/Madam,

I am writing to formally bring to attention a continuing structural issue in the implementation of

the National Education Policy (NEP) 2020, specifically in the context of Computer Science

education and subject eligibility at the senior secondary and undergraduate levels.

Even today, a student aspiring to pursue Computer Science or Computer Science Engineering

is effectively required to study Physics, Chemistry, and Mathematics (PCM) in Classes XI and

XII. This requirement exists not because all three subjects are academically essential for

Computer Science, but because most Indian colleges including premier institutions continue to

rely on PCM-based entrance examinations as the primary eligibility filter.

Institutions such as IITs, NITs, and other leading engineering colleges predominantly use

JEE-based examinations, which are heavily weighted toward Physics and Chemistry along with

Mathematics. While this assessment framework may be appropriate for several traditional

engineering disciplines, it creates a significant mismatch when applied to Computer Science.

Computer Science today is not merely another engineering branch. It is a discipline

fundamentally rooted in mathematics, logic, algorithms, computation, and systems thinking.

However, under the current admission framework, a student’s eligibility for top Computer

Science programs is often influenced more by performance in chemistry reactions or physics

derivations than by demonstrated aptitude in mathematics, programming, or computational

reasoning.

The prevailing assumption appears to be that if a student can clear a highly competitive

PCM-based entrance examination, they can subsequently learn Computer Science from scratch

during college. This approach overlooks the fact that many students who are genuinely strong in

mathematics and computing are required to invest substantial time and effort in subjects that are

neither aligned with their interests nor directly relevant to their intended field. As a result:

- Schools continue to mandate PCM combinations because college eligibility criteria demand

them.

- Colleges retain PCM-based eligibility norms because school-level subject structures remain

unchanged.

- The flexibility and multidisciplinary intent of NEP 2020 remains largely theoretical for Computer

Science aspirants.

Even in cases where a school may be willing to offer alternative subject combinations such as

Mathematics with Computer Science, students face significant barriers at the college admission

stage, where PCM and JEE-based screening remain the dominant criteria. At present, there is

no widely accepted, dedicated entrance or assessment framework that evaluates Computer

Science aptitude, programming ability, or computational thinking for undergraduate admissions.

Given that Computer Science forms the foundation of modern digital infrastructure, innovation,

and governance systems, this continued treatment of the discipline as a subset of a generalized

engineering entrance framework raises important concerns.

I respectfully submit that without coordinated reform in higher-education eligibility norms

particularly for Computer Science the objectives of NEP 2020 regarding flexibility,

multidisciplinary learning, and skill-based education will remain difficult to realize in practice. I

would request the concerned authorities to consider reviewing this issue and exploring

Computer Science specific eligibility or assessment models, such as greater emphasis on

Mathematics and Computer Science aptitude for CS-focused undergraduate programs.

Thank you for your time and consideration.

Yours sincerely,

[My name]

Student

India

and i am not saying here anything like make paper easy or anything like that but asking about testing relevant things not illogical things and if we can have medical and engineering as separate we can have others too just asking about like ask advanced mathematics logical questioning cs snippets for those debugging type things and with maths cse coding theory iq and much paper can be made even harder but it will be logical and relevant i am not saying make all people give this exam like for mechical electrical I think jee is good they give that but asking to cse one that is illogical I think system want us to leave your passion learn shits only bcz to enter in system and learn from scratch and even inside too syllabus is much outdated mostly self learn even they made NEP2020 as to start but 6 years happened almost nothing I saw on ground level forget that even for many years even imo champs who were getting admission to mit harward oxford world top 10 University who were offering direct admission even they were rejected from iit only bcz not good in all 3 until recently even that didn't changed recently some iit started but even now massive issues and for normal people it's nothing

INDIAN EDUCATION SYSTEM ELIMINATES PEOPLE NOT SELECTS THEM

What are your thoughts guys kindly tell

u/iKamiTenchi — 6 days ago
▲ 5 r/CMI

Group for discussion of CMI Msc DS

i have made a group for cmi msc data science for those who gave exam this year
if you want to join and discuss, DM me
only those who gave msc ds exam

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u/Old_Cartographer_434 — 6 days ago
▲ 5 r/CMI+2 crossposts

ISI/CMI 2027 Prep Helper

One thing I realised while preparing for ISI/CMI this year is that most people already have enough PDFs/materials. The bigger issue is usually:
• lack of good tests
• lack of serious discussion
• inconsistency
• no proper feedback/checking

A small serious prep environment honestly helps much more than endlessly collecting resources.

A few friends and I (2026 aspirants) are trying to build something around that idea on Telegram — mainly focused on:
• original topicwise/full tests
• curated materials
• original handouts
• discussions/guidance
• proper checking instead of just dumping papers

It’s not a lecture course or coaching, more like a structured prep-helper/testing community for serious aspirants.

We’ll also conduct some sample mocks with discounts for interested students.

(Will upload my own ISI/CMI results too once released.)

If anyone wants details or just wants to discuss ISI/CMI prep in general, feel free to DM in telegram:
@IllogicalCipher

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u/AR1NDAMM — 5 days ago
▲ 7 r/CMI

Cmi for bsc in physics?

Mostly everyone I've talked to is preparing for cmi to get into cs, but I myself am really interested in physics as well and maths and am looking to pursue either or both of them, and so a bsc in maths and physics seems perfect but considering how everyone is doing it for cs, is the physics department not that good? sorry if this seems ignorant

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u/gvrlicsoup — 4 days ago
▲ 4 r/CMI+1 crossposts

CMI MSc Data Science 2026 – what’s a safe score for General category?

Getting a bit anxious as the result dates are getting closer 😅 Just wanted to know what could be considered a safe score for the General category

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u/AskMeMaybeNot — 7 days ago
▲ 2 r/CMI

Part A problem in DS paper

Does anyone correctly remember the exact solution of the problem No of surjective functions from 1,2,3,4 to 1,2,3. f(1)=1,f(2)=2???

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u/Ok_Steak9670 — 6 days ago
▲ 3 r/CMI

Part A problem in ds paper

There was a problem in part A of Probability. I barely remember the problem but it included two fair dice and one random variable. Can anyone recall the exact problem? Some expectation we had to calculate. One option was 1/36.

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u/Ok_Steak9670 — 9 days ago
▲ 10 r/CMI

Summer Internship Scenario At CMI

Can anyone tell about current internship and placement scenario for CMI MSC Data Science?Alumni before 2024 used to get internships in good companies but when I checked profiles of current students on linkedin they are not like previous it seems most students doing their internships in small scale companies.

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u/Salt_Ninja_5281 — 8 days ago
▲ 4 r/CMI+1 crossposts

How was your msqmba exam?

I personally feel it was on a tougher side compared to last year. Any thoughts?

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u/itz__nemo_ — 11 days ago