In which of the following years were Ananya and Bhaskar Gurubhai?
Solution
Ananya and Bhaskar were Gurubhai under Raghunath in 2019–20, so .
5 sets, 22 questions, in exam order.
Ananya Raga, Bhaskar Tala, Charu Veena, and Devendra Sur are four musicians. Each of them started and completed their training as students under each of three Gurus — Pandit Meghnath, Ustad Samiran, and Acharya Raghunath between 2013 and 2024, including both the years. Each Guru trains any student for consecutive years only, for a span of 2, 3, or 4 years, with each Guru having a different span. During some of these years, a student may not have trained under these Gurus; however, they never trained under multiple Gurus in the same year. In none of these years, any of these Gurus trained more than two of these students at the same time. When two students train under the same Guru at the same time, they are referred to as Gurubhai, irrespective of their gender.
The following additional facts are known.
1. Ustad Samiran never trained more than one of these students in the same year.
2. Acharya Raghunath did not train any of these students during 2015-2018, as well as during 2021-24.
3. Ananya and Devendra were never Gurubhai; neither were Bhaskar and Charu. All other pairs of musicians were Gurubhai for exactly 2 years.
4. In 2013, Ananya and Bhaskar started their trainings under Pandit Meghnath and under Ustad Samiran, respectively.
Raghunath can only teach in 2013–14 and 2019–20, so his span is 2 years. Samiran and Meghnath have spans 3 and 4.
Samiran teaches one student at a time, so Gurubhai pairs can form only under Meghnath or Raghunath.
In 2013 Ananya is with Meghnath and Bhaskar with Samiran, so Raghunath's 2013–14 block must be Charu and Devendra (their 2 Gurubhai years). His 2019–20 block is Ananya and Bhaskar (their 2 years).
Ananya–Charu and Bhaskar–Devendra must each overlap for exactly 2 years under Meghnath. Charu can't start before 2015, so Ananya's Meghnath block (from 2013) must run to 2016: Meghnath's span is 4 and Samiran's is 3. Charu: Meghnath 2015–18.
Samiran's four 3-year blocks fill 2013–24 exactly: 2013–15 Bhaskar, 2016–18 Devendra, 2019–21 Charu, 2022–24 Ananya.
Bhaskar's Meghnath years: 2021–24. Devendra must overlap him by 2 years: Meghnath 2019–22.
| Student | Meghnath (4) | Samiran (3) | Raghunath (2) |
|---|---|---|---|
| Ananya | 2013–16 | 2022–24 | 2019–20 |
| Bhaskar | 2021–24 | 2013–15 | 2019–20 |
| Charu | 2015–18 | 2019–21 | 2013–14 |
| Devendra | 2019–22 | 2016–18 | 2013–14 |
In which of the following years were Ananya and Bhaskar Gurubhai?
Ananya and Bhaskar were Gurubhai under Raghunath in 2019–20, so .
In which year did Charu begin her training under Pandit Meghnath?
Charu began with Meghnath in .
In which of the following years were Bhaskar and Devendra Gurubhai?
Bhaskar (2021–24) and Devendra (2019–22) overlap under Meghnath in 2021–22, so .
Which of the following statements is TRUE?
Charu trained under Samiran in 2019–21, so she was with him in 2019.
In how many of the years between 2013-24, were only two of these four musicians training under these three Gurus?
Students training each year: 2013: 4, 2014: 4, 2015: 3, 2016: 3, 2017: 2, 2018: 2, 2019: 4, 2020: 4, 2021: 3, 2022: 3, 2023: 2, 2024: 2.
Years with only two: 2017, 2018, 2023, 2024, i.e. .
The following charts depict details of research papers written by four authors, Arman, Brajen, Chintan, and Devon. The papers were of four types, single-author, two-author, three-author, and four-author, that is, written by one, two, three, or all four of these authors, respectively. No other authors were involved in writing these papers.


The following additional facts are known.
1. Each of the authors wrote at least one of each of the four types of papers.
2. The four authors wrote different numbers of single-author papers.
3. Both Chintan and Devon wrote more three-author papers than Brajen.
4. The number of single-author and two-author papers written by Brajen were the same.
Papers: 10 single, 4 two-author, 3 three-author, 2 four-author. Author totals: Arman 5, Brajen 8, Chintan 12, Devon 10.
Every author is on both four-author papers. Brajen: singles two-author, so ; three-author must be even, so Brajen has 2 of each type.
Chintan and Devon wrote more three-author papers than Brajen, so 3 each, and Arman 1 (total incidences 9).
Three-author papers: , , .
Singles are distinct and sum to 10: . Arman: , so 1 single and 1 two-author paper. Brajen has 2 singles, so Chintan and Devon have 3 and 4.
Two-author incidences : .
Case 1: Chintan 3 singles, 4 two-author; Devon 4 singles, 1 two-author.
Case 2: Chintan 4 singles, 3 two-author; Devon 3 singles, 2 two-author.
What was the total number of two-author and three-author papers written by Brajen?
Brajen: 2 two-author 2 three-author .
Which of the following statements is/are NECESSARILY true?
i. Chintan wrote exactly three two-author papers.
ii. Chintan wrote more single-author papers than Devon.
Chintan has 4 two-author papers in Case 1 and 3 in Case 2, and has fewer singles than Devon in Case 1. Neither statement must hold.
Which of the following statements is/are NECESSARILY true?
i. Arman wrote three-author papers only with Chintan and Devon.
ii. Brajen wrote three-author papers only with Chintan and Devon.
The three-author papers are and two copies of . Both statements are true.
If Devon wrote more than one two-author papers, then how many two-author papers did Chintan write?
Devon has more than one two-author paper only in Case 2, where Chintan has .
There are six spherical balls, B1, B2, B3, B4, B5, and B6, and four circular hoops H1, H2, H3, and H4.
Each ball was tested on each hoop once, by attempting to pass the ball through the hoop. If the diameter of a ball is not larger than the diameter of the hoop, the ball passes through the hoop and makes a “ping”. Any ball having a diameter larger than that of the hoop gets stuck on that hoop and does not make a ping.
The following additional information is known:
1. B1 and B6 each made a ping on H4, but B5 did not.
2. B4 made a ping on H3, but B1 did not.
3. All balls, except B3, made pings on H1.
4. None of the balls, except B2, made a ping on H2.
A ping means ball hoop.
H2: only B2 passes, so B2 is the smallest ball and H2 is smaller than every other ball. H1: everyone except B3 passes, so B3 is the largest ball.
H3: B4 passes, B1 doesn't, so . H4: B1, B6 pass, B5 doesn't, so . And .
Hoops: , so .
Pings: B2 passes all 4; B3 none; B1 on H1, H4 (2); B4 on H1, H3, H4 (3); B5 on H1 only (1); B6 on H1, H4 and maybe H3 (2 or 3).
What was the total number of pings made by B1, B2, and B3?
.
Which of the following statements about the relative sizes of the balls is NOT NECESSARILY true?
B6 and B1 are both at most H4, but their order isn't fixed, so is not necessarily true.
Which of the following statements about the relative sizes of the hoops is true?
.
What BEST can be said about the total number of pings from all the tests undertaken?
or .
The Sustainability Index (SI) of a country at a point in time is an integer between 1 and 100. This question is related to SI of six countries - A, B, C, D, E, and F - at three different points in time - 2016, 2020, and 2024. The plot represents the exact changes in their SI, with X-coordinate representing % increase in 2020 from 2016, i.e., (SI in 2020 minus SI in 2016) / (SI in 2016), and Y-coordinate representing % increase in 2024 from 2020. At any point in time, the country with highest SI is ranked 1, while the country with the lowest SI is ranked 6. The following additional facts are known.
1. In 2016, B, C, E, and A had ranks 1, 2, 3, and 4 respectively.
2. F had lower SI than any other country in 2016, 2020, and 2024.
3. In 2024, E was the only country with SI of 90.
4. The range of SI of the six countries was 60 in 2016 as well as in 2024.

From the plot (2016→2020, 2020→2024): A (+25%, +50%), B (−25%, −25%), C (−20%, +40%), D (+100%, +20%), E (+25%, +20%), F (+100%, −25%).
E: .
All SIs are integers. B needs to be a multiple of 16, and C a multiple of 25. C (rank 2) lies between 60 and B, so C = 75 and B is 80 or 96.
2016 range 60: F = B − 60 = 20 or 36. F's 2024 value , and 2024's range is 60 with a maximum of at most 100, so F = 20 (2024: 30, max 90 = E).
So B = 80, C = 75, F = 20 in 2016.
What was the SI of E in 2016?
E in 2016 .
What was the SI of F in 2020?
F in 2020 .
What was the SI of C in 2024?
C in 2024 .
What was the SI of B in 2024?
B in 2024 .
The two most populous cities and the non-urban region (NUR) of each of three states, Whimshire, Fogglia, and Humbleset, are assigned Pollution Measures (PMs). These nine PMs are all distinct multiples of 10, ranging from 10 to 90. The six cities in increasing order of their PMs are: Blusterburg, Noodleton, Splutterville, Quackford, Mumpypore, Zingaloo.
The Pollution Index (PI) of a state is a weighted average of the PMs of its NUR and cities, with a weight of 50% for the NUR, and 25% each for its two cities.
There is only one pair of an NUR and a city (considering all cities and all NURs) where the PM of the NUR is greater than that of the city. That NUR and the city both belong to Humbleset.
The PIs of all three states are distinct integers, with Humbleset and Fogglia having the highest and the lowest PI respectively.
Only one NUR beats only one city, and both are in Humbleset. Any NUR above a city is above all smaller cities too, so that city must be the smallest, Blusterburg, and Humbleset's NUR lies between Blusterburg and Noodleton. The other two NURs are below all cities.
So: NURs 10, 20; Blusterburg 30; Humbleset NUR 40; Noodleton 50, Splutterville 60, Quackford 70, Mumpypore 80, Zingaloo 90.
Humbleset PI (x = its other city) must be an integer, so x is 50, 70 or 90. For the other states, the two city PMs must add to a multiple of 20.
x = 50 or 70 makes another state's PI at least Humbleset's. x = 90 gives Humbleset 50, and the remaining cities pair as {50, 70} and {60, 80}.
NUR 10 + {50, 70}: 35 (Fogglia, lowest). NUR 20 + {60, 80}: 45 (Whimshire). (The other pairing gives a tie at 40.)
What is the PI of Whimshire?
Whimshire: .
What is the PI of Fogglia?
Fogglia: .
What is the PI of Humbleset?
Humbleset: .
Which pair of cities definitely belong to the same state?
Noodleton (50) and Quackford (70) are both in Fogglia.
For how many of the cities and NURs is it possible to identify their PM and the state they belong to?
Every PM and state is fixed: all .
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