Problem Solving

Tommy Wallach wrote:Hey Hemant,


First step. Before posting a question, please make sure there are no typos or errors. Even a couple missing words can make a question mega-confusing for folks, and I see a couple errors here. Also, this is not remotely a realistic question. There are no questions on the GMAT that require you to do problem solving math and then have an answer choice "none of the above". It does not happen. On may levels, this is NOT a realistic GMAT question. ALSO, the given information has a BUNCH of unnecessary information, which doesn't happen on the GMAT. In short, this is a ridiculous question. Now, onwards!

We know that a 50km journey that lasts 30 minutes and has 18 carriages, 100kg of coal is consumed.

The original velocity was 50/30 km per minute, or 5/3 . The new velocity is 42/28, or 3/2.

That relationship, (5/3)/(3/2), or 10/9, represents the square root of the quantity of coal per kg relationship, so that relationship should be 100/81.

We already know that the first journey required 2kg of coal per km, so:

2/x = 100/81 162 = 100x x = 1.6

42 * 1.6 = 67.2

So I guess the answer is None of the Above. Which would never happen on the GMAT. Ever. : )

-t

hemant_rajput wrote:

Tommy Wallach wrote:Hey Hemant,


First step. Before posting a question, please make sure there are no typos or errors. Even a couple missing words can make a question mega-confusing for folks, and I see a couple errors here. Also, this is not remotely a realistic question. There are no questions on the GMAT that require you to do problem solving math and then have an answer choice "none of the above". It does not happen. On may levels, this is NOT a realistic GMAT question. ALSO, the given information has a BUNCH of unnecessary information, which doesn't happen on the GMAT. In short, this is a ridiculous question. Now, onwards!

We know that a 50km journey that lasts 30 minutes and has 18 carriages, 100kg of coal is consumed.

The original velocity was 50/30 km per minute, or 5/3 . The new velocity is 42/28, or 3/2.

That relationship, (5/3)/(3/2), or 10/9, represents the square root of the quantity of coal per kg relationship, so that relationship should be 100/81.

We already know that the first journey required 2kg of coal per km, so:

2/x = 100/81 162 = 100x x = 1.6

42 * 1.6 = 67.2

So I guess the answer is None of the Above. Which would never happen on the GMAT. Ever. : )

-t

Hey Tommy,

Thanks for the solution. I'm sorry for the typo.
The reason why my question is having option, "none of these", because these questions are CAT Exam questions( similar to GMAT exam). I didn't know that the GMAT question don't have "None of these" as there option , but you can see that CAT do. My thought process was, if I can solve a question, it doesn't matter to which exam it belong. Although, now I clearly see that it matters. I'll keep that in mind before posting any question over here.

jkaustubh wrote:

hemant_rajput wrote:

Tommy Wallach wrote:Hey Hemant,


First step. Before posting a question, please make sure there are no typos or errors. Even a couple missing words can make a question mega-confusing for folks, and I see a couple errors here. Also, this is not remotely a realistic question. There are no questions on the GMAT that require you to do problem solving math and then have an answer choice "none of the above". It does not happen. On may levels, this is NOT a realistic GMAT question. ALSO, the given information has a BUNCH of unnecessary information, which doesn't happen on the GMAT. In short, this is a ridiculous question. Now, onwards!

We know that a 50km journey that lasts 30 minutes and has 18 carriages, 100kg of coal is consumed.

The original velocity was 50/30 km per minute, or 5/3 . The new velocity is 42/28, or 3/2.

That relationship, (5/3)/(3/2), or 10/9, represents the square root of the quantity of coal per kg relationship, so that relationship should be 100/81.

We already know that the first journey required 2kg of coal per km, so:

2/x = 100/81 162 = 100x x = 1.6

42 * 1.6 = 67.2

So I guess the answer is None of the Above. Which would never happen on the GMAT. Ever. : )

-t

Hey Tommy,

Thanks for the solution. I'm sorry for the typo.
The reason why my question is having option, "none of these", because these questions are CAT Exam questions( similar to GMAT exam). I didn't know that the GMAT question don't have "None of these" as there option , but you can see that CAT do. My thought process was, if I can solve a question, it doesn't matter to which exam it belong. Although, now I clearly see that it matters. I'll keep that in mind before posting any question over here.

In my opinion there is a lot of difference between CAT and GMAT. The level of quant questions in CAT is much higher than those asked in GMAT. Also as Tommy pointed out that there is no none of these options in GMAT. Hemant, these questions are more relevant in sites like Pagalguy.com