Cbse Board Maths Exam Paper Query

Please help me with a doubt in my daughters recently held board exam maths paper..please have patience as this is going to be a long post

I have attached the image of the case study problem below.



The question is to write a quadratic equation in terms of width of the pool and then to find the value of the width.
Most of the kids have done it in the following way
L*B =36
(7-2x) (12-2x) =36
84-14x-24x+4x^2 = 36
4x^2-38x+84-36=0
4x^2-38x+48=0
2x^2-19x+24=0
Product 48
Sum 19
And so on and finally they all have got the value of x as 3/2. Almost all of the youtube videos which discussed the maths paper's solutions also have followed the same method.
This method has been followed keeping x as the width of one side of the sidewalk and hence the width(x) they have got is also for one side of the sidewalk.

My daughter has done the problem with a different approach. I have given below the workings
L*B =36
(7-x) (12-x) =36
X^2-19x+48 =0
X=3 m
Now she has taken x as the width of the whole sidewalk, formed the quadratic equation and hence got the value of the same.

Isn't this also correct? But all the kids in school and youtube videos(I asked the same query in the comments section) are saying that my daughter may or may not get marks for the width but definitely not for the equation.

We generally don't discuss the question after the exam, But this time, this question was largely discussed after the exam because these concepts were learnt in 8th grade and in their current 10th grade, specially the quadratic equation chapter they are doing completely different problems. So when suddenly a problem type which they haven't worked out in their grade came all the kids in school discussed and my daughter said that this is how she formed the equation. Now she is upset that none of them are getting her point and that she will loose all 4 marks since the youtube videos too are using the first approach and probably the official answer key will have the same solution since that's what 90 percent of the people have done. And she is prone to silly mistakes, so she is not sure where else she will loose marks. She put in a lot of hardwork and also has scored full in maths in her first term. She couldn't take that she will loose marks for something which she has done right. All my consolation is falling in to deaf ears. I want to help my child. Can someone pls tell me how to take this to the notice of CBSE and how to actually make them see my message.

 

Thank you for your reply malstrom. She doesn't go to tuitions and her school maths teacher is not that friendly enough to approach. So my daughter is hesitant.

 

Thank you Rihana for your detailed reply. True everything in life is a learning experience and the point about talking to the teacher made by you and malstrom is valid. I will suggest it to my dd one more time, may be after all the exams are over. As you said revaluation is just waste of money. They don't actually look in to the correctness of a question or answer. Only retotaling. My niece had a bad experience too. She was expected to be the school topper but the results were totally unexpected. Once the board results come all the schools put up the toppers name in the board. They don't wait for revaluation. And to help the child even if we apply for revaluation, it doesn't always turn fruitful. I still remember how she cried. Yes now she is in her final year of college and understands 10th marks are not something you cry for, yet at that time it was difficult that her haedwork didn't pay off. How much ever we hail hard work, that alone isn't enough all the time. As you said it would have been so much better if questioner had the X marked as you have done in the picture. I have already posted in the SM. But I don't know if that's enough to bring the attention. Probably many should join the request which is again difficult as most have used the first approach. We can only try. Rest in God's hands.

 

Thanks sir for your reply. You have formed the equation assuming x as the width of one side of sidewalk and the value of x will be 3/2 per your equation. If we assume x as the width of both sides of the sidewalk then we don't have to subtract 2x but only x and we will get the value of width as 3m which when divided by 2 will give the width of one side of the sidewalk. Isn't both answers the same? But 90 percent people have done it your way. I feel what my daughter has done is also right and she should get full marks for this question. The question simply states x is the width, but doesn't specifically mention its the width of one side of the sidewalk.
If we subtract 3 from the length and breadth, the length and breadth becomes 4 and 9 respectively. If we subtract 2*3/2 from length and breadth they become 4 and 9 again. So shouldn't both approaches be given marks