A group of paleobotanists collected samples of sediments containing po : Two-part Analysis (TPA)

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25 May 2024, 10:57

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The key is to focus on the word "greater ratio" which implies that we want the numerator to be higher and denominator to be lower for S1. Since S1 definitely has greater number of spores than S2 and smaller no. of species than S2. Spores and species are the correct answers.

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09 Aug 2024, 05:06

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______________S1______________S2
Pollen Grains......P & Q

Spores...............Greater number.......Q

Species Rep.....................................Greater number

Among these two samples, S1 had the greater ratio of total number of ___1___ (x) to total number of ___2___ (y).

Let
x_1: (...) of S1
x_2: (...) of S2
y_1: (...) of S1
y_2: (...) of S2

$\frac{x_1}{y_1} > \frac{x_2}{y_2}$

=> it should be
(i) $x_1 > x_2$
(ii) $y_1 < y_2$

(It can also be either (i) or (ii) but then the other equation must be "=")

x => Spores
y => No. of Species represented

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27 Aug 2024, 12:03

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Hi,

Can someone please identify issue with my approach.
IMO it should be 1. Spores 2. Spores from Species Q

S1 - Contains more spores divided between Species P and Q
S2 - Contains fewer spores all belonging to Species Q

So (Spores/Spores from Species Q) is always going to be 1 for S2, as all come from species Q.
Whereas (Spores/Spores from Q) is always going to be > 1 as S1 contains some spores from species P.

This made me go for 1. Spores 2. Spores from Species Q.

Also since the author has mentioned P and Q as species, one can also confuse "species represented" as 2 in S1 as it contains P,Q and 1 in S2 as it only contains Q. So the language seemed a little ambiguous to me.

Thanks!

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28 Aug 2024, 10:35

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ritik0212

Hi ritik0212

As you pointed out Spores/Spores from Q for S2 will be 1. Since all of its spores are from Species Q

But our question is regarding S1 (Sample 1)

Since we dont know the background of spores from S1,

Case 1: I am considering a total of 100, contributed completely from species Q
So between S1 & S2 Spores/sproes from Q remains same

Case 2: I am considering a total of 100, contributed completely from species P
So the ratio (Spores/Spores from Q) between S1 & S2 will be higher for S1

coming to the no.of species since we know that no. of species are lower for S1
Spores of S1/Species of S1 > Spores of S2(Contributed only from Q)/Species of S2

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Thank You

reeyab

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24 Nov 2024, 02:56

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KarishmaB

Quote:

All Data Insight question: TPA [ Official Guide DI Review 2023-24]

A group of paleobotanists collected samples of sediments containing pollen and spores from various plant species. Each sample was analyzed to determine the number of spores in the sample, the number of pollen grains in the sample, and the species to which those spores and pollen grains belong. Samples S1 and S2 were collected and analyzed in this way. For these two samples:

S1 had the greater total number of spores, and it contained pollen grains from Species P as well as spores from Species Q.
S2 had the greater total number of species represented, and all of the spores it contained were from Species Q.

Statement: Among these two samples, S1 had the greater ratio of total number of ___1___ to total number of ___2___.

Select for 1 and for 2 the options that complete the statement so that it is accurate based on the information provided. Make only two selections, one in each column.

Comparison:

............S1...........................................................................S2
Higher Spores (say 100)..........................................Lower Spores (say 90)
Pollen from P............................................................. -
Spores from Q (some of the 100)...........................All spores were from Q (all 90)
Fewer Species (say 8).............................................More species (say 10)

Statement: Among these two samples, S1 had the greater ratio of total number of ___1___ to total number of ___2___

S1's ratio of Spores:Number of Species will be greater than that of S2 for sure. Why? Because it has more spores and fewer species. So numerator is greater and denominator is lower.
$\frac{100}{8} > \frac{90}{10}$
ANSWER: Spores : Species Represented

Will anything else work? No. How about spores:spores from Q?
For S2, that will be 90/90 = 1. For S1, it could be 1 or it could be higher. (100/100 or 100/10 etc.)

Here is a video discussing how to handle Two Part Analysis Questions.

How can you say the species are 8 & 10 and not 200 & 300?

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03 Dec 2024, 04:25

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We can assume any numbers we want. Also we are looking at the ratio so that helps.
We just need to look at the restrictions.

reeyab

KarishmaB

Quote:

All Data Insight question: TPA [ Official Guide DI Review 2023-24]

S1 had the greater total number of spores, and it contained pollen grains from Species P as well as spores from Species Q.
S2 had the greater total number of species represented, and all of the spores it contained were from Species Q.

How can you say the species are 8 & 10 and not 200 & 300?

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06 Dec 2024, 11:10

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can it be 1->spores and 2->spores from Species Q. as spores in s1 > spores in s2, so ratio is >1 where in s2 it is 1

like for s1 ratio =spores/(spores from q)>1 as spores from q = spores from s2 but spores(s1)>spores(s2) .. given and for s2 ratio it is 1.
plz help

chetan2u

S1 had the greater total number of spores, and it contained pollen grains from Species P as well as spores from Species Q.
S2 had the greater total number of species represented, and all of the spores it contained were from Species Q.

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06 Dec 2024, 11:46

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you are talking about ratio of (total number of Spore) : (Spores from Species Q)
for both samples.

The issue here is
1) in S1 --> it only says that it has the greater number of total Spores when compared with both samples And S1 contains Spores from Species Q. It doesn't say anything about if S1 contains Spores from other Species or not so it could be that all the Spores in S1 are from Species Q or maybe not. so the ratio could be anything from 1 to less than 1.

Now let's say that we still want to compare, we need to know that there is a clear comparison from these specific items used in the ratio in S1 and S2 then

2) In S2 --> We know all the Spores are from Species Q so that ratio becomes exactly 1.

In this case, your mentioned solution still not always be true. (because of the point 1) and we want a sure answer which we can get from
#of Spores : # of Species represented

Among these two samples, S1 had the greater ratio of total number of ___1___ to total number of ___2___

Hope this helps. I tried my best

jp11

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12 Dec 2024, 03:19

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jp11

chetan2u

S1 had the greater total number of spores, and it contained pollen grains from Species P as well as spores from Species Q.
S2 had the greater total number of species represented, and all of the spores it contained were from Species Q.

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ID: 700266

We need item1/item2 to be greater for S1. So numerator (item1) has to greater for s1 than s2. Denominator s1 should have lower value than s2.
We are given s1 has total spores greater so that could be the numerator. We are given s2 has higher species that is s1 has lower count for species.

Unless I missed something it’s that simple.

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10 May 2025, 08:38

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Among these two samples, S1 had the greater ratio of total number of ___1___ to total number of ___2___.
In order to get any ration (A/B) to be as great as possible, we need to maximize the numerator (A) and minimize the denominator (B). In the prompt, we can only know for a fact that S1 has more spores and fewer number of species than does S2. So spores goes to blank 1, and number of species presented goes to blank 2.

Here is the fun part, the GMAT would always try to pull some mind trap if you are not careful. Here are some of the traps that came up in my mind before getting discarded.

S1 had the greater total number of spores, and it contained pollen grains from Species P as well as spores from Species Q.
1. Does S1 only have grains from Species P and spores from Species Q? No, it could have something else, i.e. grains from Species Z.
2. Does S1 only have Species P and Q? No, we just know Species P and Q are in the set, and do not know about other species.
3. Does S1 have more Species Q's spore than that in S2? No, we don't know. Might be the case that Species Q only accounts for a very small amount of total number of species in S1.

S2 had the greater total number of species represented, and all of the spores it contained were from Species Q.
1. Does that mean S2 has less species Q's pores than does S1? We don't know. It might be the case that Q's pore from S2 is more than that in S1 while the total of number of spores in S2 is still less than that in S1 (because S1 may have a lot more spores from other species as well)
2. Does that mean S2 only have species Q? No, because it is explicitly stated that S2 has more species than S1, so at the minimum S2 has 3 species (because S1 already has species P and Q)