The SAT Guessing Guide 2015

Some questions on the SAT are easy enough that you know the answer as soon as you read the question. Some questions are hard enough that you can’t choose from any of the five options. However, the most exasperating type of question is one in which you can comfortably eliminate three answer choices, but never be able to decide between the other two. Every time I faced a question like this on the SAT I wondered, what is the best possible guess I can make between those two answer choices?

My objectives were twofold:

  • to find the best possible single answer choice for each section (Reading, Writing and Math)
  • to find the most probable pair of answer choices for each section, i.e. to which two answer choices occurred the most in pairs

I used 11 actual SAT papers to do my analysis, and analysed over 1700 answer choices. At the end of the analysis, I arrived at some interesting conclusions. (You can find the entire excel sheet here).

A couple of quick notes before I share my results.

  • None of this data is to be used as a substitute for common sense. If you know an answer is wrong (or right), choose that over anything statistics might tell you. 
  • Wherever I have said that probabilities are reasonably higher, it only means that they are higher than their expected values. This does not mean that they are significantly large.


As expected the number of A, B, C, D and E answer choices were all around 20%. The deviation from 20% was very low, with a standard deviation of only 1.8%. The most likely single correct answer was D, with 22.7% of the share. Nothing interesting so far.

Now for the paired answers, and this is where it really gets interesting. The most common pair is CD, with 5.7% of the share. But what is more interesting is the second most common option, AD (5.1% of the total). Viewed in isolation, AD is quite boring. However, when you observe that A & D independently constitute the two most probable options (for the single correct answers), it makes a considerable difference. This is because both the individual and paired probabilities of A & D are high. This means that the likelihood of getting AD (in that order) is reasonably higher than the likelihood of any other pair of options on the Reading section.


To save your eyes some trouble, I’m going to tell you that the Math section is exactly like the Reading section in terms of the single correct options, except that the standard deviation is lower, at 1.3%. D is again the most common option with 21.5% of the share.

The paired answers are more revealing in Math than they are in any other section. Just like in the Reading section, AD is the most common option. However, two things further boost the probability of D & A. Firstly, the DA pair is the third most common option. Secondly, A & D are the two most common individual occurrences. Since AD, DA and A & D(individually)are all more likely, the probability of these pairs being the right answer is reasonably higher than the probability of any other pair being correct.


Option C takes has the highest probability here with  a 23.9% chance of occurrence. There is a standard deviation of 2.9% in this section, with the percentages for each option hovering near 20%. However, option A has an unusually low occurrence of only 15.8%.

The conclusions in this section are similar to those of the previous sections. BC is the 2nd most common pair (5.6%) and CB is the 3rd most common pair (5.2%). B & C are individually the two most likely options. Using arguments similar to those used for the previous two sections, it is evident that the pair BC (in any order) has a reasonably higher likelihood of being right than any other pair does.


The overall analysis is quite lackluster. All the options have a very similar individual likelihood, and the most common pairs don’t contain the most common letters (unlike the individual sections).

So there it is, my analysis of the SAT test options. Hopefully, you won’t be as confused anymore when you have to pick between two answers on the SAT!


The Antics of An Ant

While I was trying to install a whiteboard on my desk, I used 3M’s double sided tape. Quick tip, never use 3M tape unless you know that you never want to remove it! I couldn’t get most of the tape off my table, and that’s the white thing you see on the table in the video. Luckily, that tape created an interesting experiment right on my table.

While I was working at my desk, I saw a fly that was stuck in the tape, and an ant that was trying to lift it off. If you saw the video, you know that the ant was successful. There were a few more experiments I conducted that produced some interesting results.

Can ants lift 10 times their own weight?

Most ants can lift atlas three times their own weight and there is well-documented research with precise capabilities of different ants noted. By scaling approximations, the ant in the above video weighs anywhere from 0.3 to 0.6 mg, while the fly weighs 2.5 to 3 mg. So the ant definitely lifts a weight much greater than its own body weight.

How much does it take to stop an ant from moving with this weight?

This was a very interesting question to answer. On the sticky tape, the ant seemed to find it very hard to move. It took the ant well over 10 minutes to escape the sticky tape prison. Once it got past that, there was a hair in front of it, which it wasn’t able to get over at all. Only when the hair was removed did it make any progress. As is evident from the video, the ant moved incredibly fast with the load on the table. Even when I blew on the ant from a 20cm distance, it walked with the load, albeit slower.

What does it take to detach the ant from its load?

From my experiments, a LOT. I wasn’t able to separate the two. I blew a gust of wind that was enough to throw the ant 20 cm away, but it still had its load with it. I then lifted the load up and shook it vigorously, but the ant still held on to the load. This led me to the conclusion that the bite of an ant is incredibly strong, and on looking it up, my guess was confirmed here.

How do ants find their way around?

Based on what I saw, and what you can see in the video, it seems to be completely random initially. The reason I say this is because the ant actually went far away from the sticky tape and then came back to that exact same spot after circling around the table. I think it needs time to find its way back.

Are ants social animals?

Ants are famous for their cooperation and group effort. However, I’m not sure that this works every time. The reason I say this is that when two other ants went near this ant, they simply walked around without sharing the  load. Even when I forced these two ants to walk right in front of the other ant by blocking all other paths, they still walked around the other ant. It seemed as though they knew that the ant was there but didn’t see the need to help. I have two theories about this. Maybe the ants actually didn’t know that the other ant was there, and maybe ant communication is not that simple. Otherwise, despite being aware of the presence of the other ant, they chose not to help because the fly wasn’t too “hard” to lift. The problem with this second hypothesis is that the first ant seemed to move slower and slower every five minutes, which might indicate that it could not bear the load without strain. Of course, I don’t know the actual reason behind this, but these reasons seem plausible to me. Let me know what you think!

A Case Study of The Pallikaranai Marsh

While clearing up my (not-so-clean) cupboard, I came across two spiral bound documents that contained two studies of the Pallikaranai Marsh in Chennai. These were studies my friends and I did when I was in the 8th grade about various aspects of the marsh. When I was going through the document, I realized that when we were doing this study, one of the biggest roadblocks we faced was a lack of easily available information about the marsh. I knew that I had to publish this document online, because it contains data that someone else might need at some point in time. So here it is. Let me know what you think!

Phase 1

Phase 2

The Abstract
‘The World has enough for everybody’s need, not everybody’s greed’ – these famous words of Mahatma Gandhi symbolize the project that we have undertaken. This project on the Pallikaranai Marsh is the first step in protecting a huge ecosystem. The ecologically-sensitive  Pallikaranai Marsh, one of the last remaining natural wetlands in south India has been deteriorating steadily due to ill – planned urbanization, destructive reclamation and dumping of solid waste.  This project deals  mainly with solid waste management and water problems. In this project there has been and is going to be research into the water and soil quality from the marsh and around to make inferences about the dangers of human intervention in this ecosystem. Our experimental Research also features GIS(Geographical Information System) and Grid  Mapping. Our major findings reveal that the marsh water is polluted, mercury level is seven times more than the permissible limit. The pot culture studies have proved that some plants may grow well when the water samples are rich In organic matter. The results of this study are truly significant  and can  help in the betterment of the locality and also motivate the civic body to start working towards protecting this marsh.

LEDing the way to A Better Future


With an energy crisis looming over the world, we tried to make the situation better by improving the efficiency of something as basic as lighting.  This project harnesses the fact that the human sees light blinking rapidly enough as a still light. This principle was applied to 10Watt LEDs used for room lighting.

A microcontroller was used to switch LEDs on and off very quickly. Power consumption of the LEDs was predicted for different combinations of on-off times for the LEDs. We hypothesised that perceived brightness wouldn’t change because the LEDs were off for a short time-period. Experiments were conducted with the LED for 1 millisecond(ms) on, 1ms off; until 1ms on, 12ms off. This was repeated for on times from 2-8ms. The power consumption and brightness of the LEDs were measured for all combinations. Power consumption of the LEDs reduced drastically. Contrary to the hypothesis, the brightness also reduced in combinations with longer LED off times (Click on graphs for clear images)


3 efficient on-off combinations were identified in 3 categories – low, medium and high brightness.  They produced 42%, 20% and 18% respectively greater brightness per watt consumed than non-blinking LEDs.

Incandescent lamps account for 25% of power consumption in lighting. They consume 6563 terawatt-hours annually. Replacing these with non-blinking LEDs results in a saving of 4923 terawatt-hours! If blinking LEDs are used, there would be an additional 328 terawatt-hours of power saved (assuming minimum efficiency), more than Germany’s annual power consumption!

As always, to view the entire project, click here. Cheers!




A project by – Raghav Anand, Rahul GS and Aniroodh Ravikumar

Descending Dreams

Air Conditioners (A/C) use roughly 1 trillion kWh of power annually. The project seeks to reduce power consumption of A/Cs. The proposal is a movable false ceiling. It will be lowered when the occupant is sleeping to reduce the volume of the room allowing the A/Cs to cool faster. The question which had to be addressed was ‘How much will reducing the volume of the room at night using a movable false roof, reduce power consumed by air conditioners?’ The hypothesis was that there was a relation between the time taken to cool the room and its volume.

The experiment tested energy savings by using a high power A/C to cool a smaller volume. Two boxes of thermocol were built, simulating a room. The first box represented the original volume of the room. The second box’s volume was adjustable. 4 tests were conducted, changing the output temperature on the A/C and the volume of the second box in each test.

All the tests pointed to two important results:

  1. The lower the volume, the greater the energy savingThere was an average power saving of 0.14 kWh/hour translating into a 14% reduction in power consumption.
  2. The lower the A/C output temperature the greater the energy saving.

Large scale implementation of such a device will result in massive energy savings worldwide. In an escalating electricity cost scenario, this device can help households to reduce power costs without compromising on comfort.

To view the entire project report, please click here. Cheers!

A Project by – Raghav Anand and Rahul GS