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Maths, Addmaths and Statistics: Post your doubts here!

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help me get to the markscheme answer of Add maths nov 2012 qp 22 Q# 7c - is it wrong in marks scheme?
 
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question.png
for this question my graph does not make up a straight line even though my values of lg p and lg v match mark scheme's values. my graph has one point above line and one point below. it roughly looks like this on a graph paper(which is accurately drawn). Untitled.png
 
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Q. The cost of a TV and a radio together is Rs. 4220. The Cost of TV set is Rs. 20 more than 6 time
that a radio. What is the cost of the radio?

A.Rs 1000
B. Rs 100
C, Rs 700
D, Rs 2500

answer with all steps :)
 
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help needed with (e) part

y=x³-2x²+1 intersect y=x+a, emilimate y u get:
x+a=x³-2x²+1
0=x³-2x²+x+1-a --(1)
question say that the equation u get on intersection is y=x³-2x²+x+1+2solve them simultaneously and u get -a=+2 or a=-2
draw the line y=x-2(value of a is -2) so the x-coordinates of intersections are values of x.
 
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y=x³-2x²+1 intersect y=x+a, emilimate y u get:
x+a=x³-2x²+1
0=x³-2x²+x+1-a --(1)
question say that the equation u get on intersection is y=x³-2x²+x+1+2solve them simultaneously and u get -a=+2 or a=-2
draw the line y=x-2(value of a is -2) so the x-coordinates of intersections are values of x.

Thank you :)
 
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Q. The cost of a TV and a radio together is Rs. 4220. The Cost of TV set is Rs. 20 more than 6 time
that a radio. What is the cost of the radio?

A.Rs 1000
B. Rs 100
C, Rs 700
D, Rs 2500

answer with all steps :)
Solu: Let cost of radio=x
Cost of Tv=6x+20
4220=6x+20
6x=4200
x=700
Option C is the answer.
 
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View attachment 23218
for this question my graph does not make up a straight line even though my values of lg p and lg v match mark scheme's values. my graph has one point above line and one point below. it roughly looks like this on a graph paper(which is accurately drawn). View attachment 23219
Have you rounded the values to 3 sig. fig.? I attempted a question like this in the mocks, 1 or 2 points were off (with a larger scale and as accurate as possible) so then I used sig. fig. values such as 10.2, 20.1 and it worked like a charm. Questions like this are very annoying. o_O
 

tdk

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Does anybody have the older Question Papers and Mark Schemes of Add Maths and Maths D from the Years 1980 to 2002? I need these urgently. could anybody help me plzzzzzzzzzzzz. Thank you in advance.
 
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Have you rounded the values to 3 sig. fig.? I attempted a question like this in the mocks, 1 or 2 points were off (with a larger scale and as accurate as possible) so then I used sig. fig. values such as 10.2, 20.1 and it worked like a charm. Questions like this are very annoying. o_O

i want to know if it is necessary that line crosses all the points OR like physics it should be a best-fit line
 
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i want to know if it is necessary that line crosses all the points of like physics it should be a best-fit line
In Physics ATP, the values given to us are experimental values, i.e. that are found using an experiment (or that's what we assume) and there is bound to be error in the values hence they write best-fit, the examiner wants to check that we know that error in values occurs even the examiner report of one of the papers stated that at least 2 points are exempted from the curve/line. But in Add.maths, the values are best fit and I've solved this chapter from my book and classified papers and never have I come across a question where we don't get a perfect curve/straight line. Its bound to be the error with the decimal points, I did it in my mocks and got all the answers correct (or within the range). Hope that clears your confusion. :)
 
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