GRE Quant Ep 1: Arithmetic & Algebra
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- čas přidán 23. 07. 2024
- Even though they're the 'basics', lots of people still struggle in a GRE quant question on fractions, roots, or factoring quadratics. Even if you 'know' lots of algebra, it can be difficult to understand exactly what a question is asking you to do. Picking numbers randomly in the hope you'll find a way through the problem is rarely a good idea, so what should you.do instead?
In this video, Harry -- a GMAT Ninja tutor -- will show you how to think about GRE arithmetic & algebra questions efficiently and effectively. He'll help you understand how a flexible, consistent approach to each question can increase your efficiency and accuracy on quant.
This is video #1 in our series of full-length GRE quant lessons. For updates on upcoming videos, please subscribe!
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For more on Harry Duthie and his penchant for bench-pressing students who refuse to do their homework: www.gmatninja.com/harry-duthi...
Chapters:
00:00 Introduction
02:02 Question 1 - Factoring Quadratics
07:05 Question 2 - Summing Fractions
10:44 Question 3 - Simultaneous Equations
18:08 Question 4 - Largest possible product
23:11 Question 5 - Relationship between variables
28:52 Question 6 - Not so intimidating quadratic
33:15 Question 7 - Word problems
38:58 Question 8 - Quadratic inequalities
45:53 Question 9 - Must be a square?
I am fully relying on your whole quant list for my exam. Hope it will totally help🤞
Weldone...
I am just starting to watch your videos and I don't even want to sleep any more, I am confident that I will pass my GRE
Haha, thank you! Make sure that you get some sleep, too -- it helps your GRE performance. :)
@@GRENinjaTutoring sir please tell the answer of 9th question its option A or B
@@LioPaul-qp7ks both
@peelolyetunembenge311 When will you be appearing for gre?
When will you be appearing for gre?
thank you so much sir for such a beautiful, Lucid and coherent way of explaining algebra and arithmetic. :)
Thank you so much for the kind words, Aditya! Have fun studying.
Great explanation. Thanks
Thank you!
What are the other things that would help if I have them memorized?
Excellent video btw
The last question if you substitute the letter P with quadratic numbers you'd solve (4, 9 , 16 , 25) them with ease , it would save more time! , thanks :) and if after you calculate it you dont get quadratic numbers than its wrong.
Thanks professor
Thank you so much for watching, Vaidehi!
@@GRENinjaTutoring sir please tell the answer of 8th question its option B or C
Invest in your channel, but some lights so we can see the board
The last question was hardest I have ever seen
Then there's me,.... got the last one (apparently the trickiest one) correct, messed up all the easy ones🙃
Sir, your videos are amazing! Like your content.
Thank you, Bharat!
"Pause the video, go away..." nice
In the third last question, can we not use the unity method? equating 20 and 36, 16 and the variable?
Yes, you can and that's essentially what Harry did in the solution. He said 20*36 = 720, so we want 16*(some variable) = 720. This is basically the same as saying 20*36 = 16*(some variable) and solving for the variable.
I hope that helps!
Square vs squre root
Also, dont get it how is x>2 and not
I'm not 100% sure which inequality you're referring to. I'm going to assume you mean the inequality written in blue text on the right-hand side of the board that was written at about 42:00, but please tell me if you're asking about a different inequality.
In this question, we want to know which values of x would make (x - 2)(x + 3) < 0. At that point of the solution, we'd established that x = -3 and x = 2 would make (x - 2)(x + 3) equal zero. The next step is to look at either side of these points to see whether (x - 2)(x + 3) is greater than or less than zero. This means we should examine what happens when x < -3, when -3 < x < 2, and when 2 < x.
When we looked at the area where 2 < x, we found that this would mean (x - 2) would be greater than zero and (x + 3) would be greater than zero. This means that (x - 2)(x + 3) would be greater than zero when 2 < x, so 2 < x does not satisfy the inequality in the question.
I hope that helps a bit, but please let me know if you have any further questions!
hi,
in the fourth question, it was stated that x and y are two-digit integers and x is less than 35, so doesn't that exclude 1 to 9 as they are single digit numbers.
my bad, i did not notice that the-question was to find the maximum value, not the range of all possible vlaues
For Q7, it says to keep its 20trucks running for 36 days not keep 20trucks EACH for 30days…so i do not understand why we multiplied :(
In this question, the number of trucks available to the company changed because 4 of the trucks failed a maintenance test. We know the company has enough fuel to keep its 20 trucks running for 36 days. This means the company has 20*36 = 720 truck-days worth of fuel.
A stock of 720 truck-days means at one extreme the company could keep 1 truck running for 720 days. At the other extreme, the company could keep 720 trucks running for 1 day. Between those extremes, there is a range of values the number of trucks and the number of days could take. In this question, we're trying to find out how many days the company could keep 16 trucks running, so we can do 720/16 = 45 to find the answer to this question.
I hope that helps!
@@GRENinjaTutoring 28.8 is the answer
@@MuhammadAbdullah-qk2dq NO bro if 20T =36days then 16T=____days so 36/4=9days 4T=9days so 16T=36+9 =45 days with decrease in trucks will automatically increase fuel days
Sir, will there be any different kind of a problem in gre or all the types are covered in the video?
Our full GRE quant video course covers all of the key quant concepts that you'll need for the exam.
The GRE can -- and sometimes does -- get creative about how it tests these quant concepts, so even if you practice every single official question out there, it's possible that a few questions will feel unusual on test day. But everything you'll see on the GRE quant section is built on the quant concepts that are covered in this series.
I hope that helps a bit, and have fun studying!
for q6, isnt it a rule that you cannot multiply both sides with a variable because you never know whether the variable is zero or not?
There are two ways of looking at this. The first (and probably the best way of thinking about this problem) is that Harry didn't multiply this equation by a variable because he didn't multiply the equation by anything at all. He said that if you have a fraction that equals zero, then the numerator of that fraction must equal zero. That's what the first line of algebra says: Harry isolated the numerator of the fraction and said that equals zero.
The second way of looking at it is to say that the eventual solution to the question is x = 1 or x = 2. If we substitute either of these options into the denominator of the original fraction then neither set of parentheses will equal zero. This means that Harry could have multiplied the equation by (x + 1)(x - 3)^2 and there wouldn't have been any problems.
It's not a rule that says you can't multiply both sides of an equation by a variable. However, it's something to be very, very careful about because you don't know whether the variable equals zero. It's usually safer to avoid doing it at all but there are situations, like this one, where you can do it.
I hope that helps!
Thanks teacher BUT I got 28.8days. Here is how I got my answer .
Let ''y'' be the number of days the company's fuel supply will last.
20truscks =36days
16 trucks = y days (since we don't know the numbers of days for 16 trucks)
Crossed multiply :) 20 y =16*36days
y=16*36days /20
y= 28.8days
Unfortunately, we can't equate 20 trucks with 36 days and we can't equate 16 trucks with y days. However, we can use the units of each quantity to try to simplify the question a little.
At the start, the company has enough fuel to run 20 trucks for 36 days, so instead of saying 20 = 36, we can multiply these numbers to get 720 truck-days of fuel. Here, we're saying that the total amount of fuel the company has in its stock is equal to the number of trucks multiplied by the number of days the company can keep that truck running. To represent this figure, we can use the made-up unit of a truck-day, where one truck-day represents the amount of fuel one truck uses per day.
This means we can divide the number of truck-days of fuel we have available by the number of trucks we want to run. If we think of the units as variables, we'd be doing truck-days / trucks and we could cancel the trucks on the top and bottom of this fraction to leave us with the number of days. Doing this with the numbers involved in the question means we'd do 720 truck-days / 16 trucks to get 45 days of fuel available.
I hope this helps!
I thought this too but it doesnt make sense logically that less trucks would last less time...
for the truck queston can't we take this method
20 trucks for 36 days
so 1 truck makes it run of 36/30 = 1.8 days
so 16 trucks will make it run for 16 x 1.8 = 28.8 days??
I did the same, but think logically, reducing the number of trucks will reduce the fuel consumption and increase days
Hi @VapTex, as @claschodes0855 says, the problem with the method you suggest is that reducing the number of trucks the company runs should increase the number of days its store of fuel lasts.
It might be easier to think about this question in terms of the units of each quantity. At the start, the company has enough fuel to run 20 trucks for 36 days, so instead of dividing 36 by 20, we can multiply these numbers to get 720 truck-days of fuel. Here, we're saying that the total amount of fuel the company has in its stock is equal to the number of trucks multiplied by the number of days the company can keep that truck running. To represent this figure, we can use the made-up unit of a truck-day, where one truck-day represents the amount of fuel one truck uses per day.
This means we can divide the number of truck-days of fuel we have available by the number of trucks we want to run. If we think of the units as variables, we'd be doing truck-days / trucks and we could cancel the trucks on the top and bottom of this fraction to leave us with the number of days. Doing this with the numbers involved in the question means we'd do 720 truck-days / 16 trucks to get 45 days of fuel available.
I hope this helps!
Things to rememeber: Can be true vs have to be true
Truck days or jour homme, i can operate 20 trucks for 36 days or 1 truck for 20*36 or16 ttruck for 20*36/16
Square vs squre root
2 digits integer donc 9
Good job. I hate this question @15:57.
Haha, thank you! And yes: that one isn't the most enjoyable question ever. :)
Have fun studying!
sir please tell the answer of last question
The answer to the final question is both (A) and (B). You'd need to select both options to get this question correct.
I hope that helps!
@@GRENinjaTutoring but isnt option d in a2 - b2 form so shouldnt it be marked aswell ?
Hi @@vishwasravikumar,
While (D) is in the a^2 - b^2 form, the result doesn't have to be a perfect square number.
If p was 169, then p - 25 = 144 and (sqrt(p) - 5)(sqrt(p) + 5) would be a perfect square. However, if p was any other number (1, 4, 9, 16, 25, 36....), then p - 25 would not be a square number.
This means option (D) doesn't have to be a square number, so it is not an answer to this question.
I hope that helps!
Seth Rogen after going bankrupt😂
And after doing a whole lot of bench presses, I guess? 😆
Your long pauses are annoying! It's not like a live class where someone watching cannot hit pause!!!
@8:14
@11:46
@20:14