GMAT math thinking skills 2

Topic: Geometry

Question Type: data sufficiency

To understand directions watch this video

The question is

What is the area? we need a numerical answer. We need some numbers to work with.

Statement 1:  AG:GE = 2:1, A ratio. No numbers. Hence not sufficient

Statement 2: AB = 10 BC= 20. Do we know the nature of the triangle (equilateral or isosceles?) no

We know that AD and BE are the two medians. The medians bisects the base into two equal parts.

The median bisects the triangle into two smaller triangle with equal areas.

 Area of triangle ABD = Area of triangle ADC

Also area of triangle ABE = Area of triangle BEC

G is the centroid so the AG: GD = 2:1 and BG:GE = 2:1

Nothing further can be arrived at. Hence statement 2 is insufficient

Let us combine both statements .. You should know what apollinius theorem is

GMAT Data sufficiency rules

Understand GMAT data sufficiency. 

There are 31 Quant questions in the GMAT.

You will get  9 to 11 data sufficiency questions

The first thing to do with a Data Sufficiency question is to learn the meaning of the options 

The answer choices are the same for every Data Sufficiency question. Therefore, you need not read the directions in the exam. You can save time... 

Watch this video and understand the directions....

 

GMAT sentence correction question - multiple errors in a sentence

Can you spot the different #GMAT sentence correction errors...

In 1974 a large area of the surface of Mercury was photographed from varying distances, which revealed a degree of cratering similar to that of the Moon’s.

(A) which revealed a degree of cratering similar to that of the Moon’s
(B) to reveal a degree of cratering similar to the Moon
(C) revealing a degree of cratering similar to that of the Moon
(D) and revealed cratering similar in degree to the Moon
(E) that revealed cratering similar in degree to that of the Moon

The intended meaning of the sentence is as follows
a large area was photographed and analysed. From that analysis the degree of catering of mercury was compared to that of the moon.

Elements that can be identified
1. Usage of a pronoun which
2. comparison..- degree of catering of mercury vs degree of catering of moon.
3. 2 clauses - A comma after distances.

Option A
Which is a pronoun . Its antecedent is Distance. Did  distance  reveal anything.. No.. Option A is ruled out.

Option B
Degree of catering of mercury is compared to moon.. That comparison is absurd. The correct comparison is Degree of catering of mercury and degree of catering of moon. Option B has an error

Option C
Revealing is a participle. The participle phrase - Revealing.... is predicated of the main subject - large area of surface. The large area  was revealing information via a photograph. The sentence structure is precise and unambiguous.  The comparison is appropriate. "That of" indicates a feature of moo. The comparison here is between feature of mercury(Degree of cratering) and feature of moon.

Option C is correct.

Option D
And indicates. that large area revealed two features.  From the intended meaning, only one feature, degree of cratering, is mentioned. Also a comparison error. ( same as option B)  Hence Option D has a multiple errors.

Option E
Which noun does "that" refers to?  Large area or photograph ?? It is not clear.  Option E is elliminated

Hence option C is the correct answer.

Hope you noticed all the errors.

If you would like to attend 20hr verbal foundation course for GMAT..contact me.. 

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GMAT math Thinking skills - 1

There are two ways to solve this problem

Approach 1 - 

This approach would require you to assume variables,write equations and solve them.

Yes!  this approach take some time

Those of you who are new to math, would, most likely, attempt a question using this approach

First :

Convert the ratio into number by introducing a constant x

The speed of the 3 runners will be 3x,4x and 5x.

Second 

Assume the distance traveled by each runner is 60 units ( 60 is the LCM of 3,4,5. You can take any number.. I took the LCM to avoid decimals.)

Speed = distance/time. Hence   Time = distance/speed

Time will be 60/3x,60/4x,60/5x. respectively = 20/x,15/x,12/x

Remove (1/x) and then you can write the numbers in a ratio: 20:15:12

Approach 2:

If you solve a mathematical question using this approach, it means you are comfortable 

• determining the nature of numbers,
• identifying  relationships between variables 
• substituting values to arrive at an answer fast

This approach would take less time than approach 1.

Now lets solve this question using this approach

You would have observed the following in the question

• ratio of the speeds are given
• distant is constant

The relationship between  speed and time is : Speed is inversely proportional to time. 

Hence if speed increases time decreases and vice versa. 

The speeds are in the ratio 3:4:5. 

Hence the times should be in the ratio: 1/3 :1/4: 1/5 as speed is inversely proportional to time. 

Multiplying with LCM (4,3,5) i.e. 60 ..............to normalize the ratio

We get 20: 15:12

The answer is 20:15:12

Take-away:

Always observe the hidden relationship between numbers

Watch this tutorial video and understand mathematical reasoning skills..

You can excel in math once you learn these skills.

Hope you understood both the methods.   

Need math help: Get in touch with me:

My linkedin profile: https://www.linkedin.com/in/georgeanand

My facebook learning group:  https://www.facebook.com/groups/semanticsGMAT

My company: https://semanticslearning.com/

Want to explore math reasoning skills further try another problem

Solution here

https://letsgmat.blogspot.com/2020/07/gmat-math-thinking-skills-3.html

8 ways to score poorly in the GMAT

Here are the top 8 ways to score poorly in the GMAT.

1. I know math,

 so no need to go through the same old arithmetic, algebra, geometry stuff. 

It is possible to get Q51 in the math section, provided you are thorough with the math concepts and you have the essential problem solving skills, which can help you crack a question in less than 30 seconds. 

2. I have tones of free downloads 

..what is relevant, what is not, even God may not know..

The cost of finding,collating and structuring free content is high.  What works for you? what doesn't work for you? Do you want to do a trial and error approach to see which plan works? 

3 . Just official guide (OG), 

what else, nothing official about it…

First build concepts, then apply the concepts on OG questions. You need to use OG at the last stage of your preparation.

4. I will join for the costliest, longest duration course in town…

let them get me the score, no need to  study at  home..

There is a popular saying : "You can lead a horse to water but you can't make it drink." 

You need to work with the GMAT tutor in tandem. Then you can maximize your score in the shortest possible time

5. I won't do the essays while practicing,

Only math and verbal mock exams will do....

Work on all the sections of the exam. The skills in the various sections ( Integrated reasoning,math,verbal. and essays) are inter-related.

6. I speak and write good English, 

so verbal is going to be a cake walk, no less

I hear this often. Only when you go deep into verbal section. You will understand the nuances. Fortunately you can get 100% accuracy in the verbal section.

7.  I need just one month for preparation,

......... after all I had high grades in college.

High grades in college doesn't guarantee you a 700+ in the GMAT. Follow the customized study plan given by the tutor. Only when you achieve the learning objective at the concepts stage, take mock tests. Only when you reach your target score in the 3 or more tests.. book for the exam.

8. Do as many tests as possible,

 in fact 90 percent of my preparation time should be spent on tests. concepts? What concepts?

Fundamentals first... ..always

Also  some notable mentions

9. My friend said GMAT was easy for him, no tough questions 

hey, what was your friend’s score?

Each test aspirant is different,  What works for your friend, may not work for you.. Get a customized study plan

10. The luck factor

Out of five tests you did, one test you scored above 650. So you will give the test as planned.  you believe in luck!

I wish life was as simple as that....

A little bit about me.

I am George, a GMAT tutor, since 2008. I coach students online as well as offline at my center. You can

• Check my linkedin profile: https://www.linkedin.com/in/georgeanand
• Join my facebook online learning community: https://www.facebook.com/groups/semanticsGMAT
• Visit my website to know about my classes:  http://www.semanticslearning.com/
• Read my thoughts on GMAT prep via my blog: https://letsgmat.blogspot.com/

GMAT math foundation course

If you are finding it difficult to study math,  Don't worry.

GMAT tests you on mathematical reasoning, not mathematical ability..  

Reasoning is an important skill, which you must develop..

1. 30 hrs online live classes

2. Ideal for students with a non-math background

3. Nominal fee... fee will be reduced if more join the batch. (Batch size max 10)

Objectives of the course:

1. Revision of basic math concepts

• numbers
• Algebra
• percentages
• ratios
• Time and work
• Geometry basics
• Discrete probability
• statistics
• Mixtures
• sets

2. Increase speed using math-accelerator series

I have worked with lots of students who have lost touch with math... so I will go slow and make sure that you understand the concepts.

Feel free to schedule a math counselling session. You can reach me - George - GMAT math tutor
Check my linkedin profile: https://www.linkedin.com/in/georgeanand

or call me @ 9884123808