Mathematics: Post your doubts here!

[soumayya]

2) Two dice, each with four faces marked 1,2,3 and 4 are thrown together.
(a) what is the most likely total score on the faces pointing downwards?
(b) What is the probability of obtaining this score on three successive throws of the two dice?

​

most likely total = 5
Probability of obtaining a total of 5 = 4/16
probability of obtaining this score on three successive throws = 4/16 * 4/16 * 4/16= 1/64

 

[emma_rodge]

Thank you so much! i am really having trouble with some of the probabilty problems!

 

[Serah]

Thank You So Much really greatful to you!!

 

[hredoymohammad]

what is the difference between stretch and enlargement?

 

[CaptainDanger]

what is the difference between stretch and enlargement?

In one way stretch either x-axis remains invariant or y-axis...

Two way stretch with same scale factor is same as enlargement...

 

[hredoymohammad]

In one way stretch either x-axis remains invariant or y-axis...

Two way stretch with same scale factor is same as enlargement...

can u tell me any link of a pdf file or anything ...relating to dis? how to do enlargement...finding the scale factor etc?

 

[CaptainDanger]

can u tell me any link of a pdf file or anything ...relating to dis? how to do enlargement...finding the scale factor etc?

Check this post : Maths, Addmaths and Statistics: Post your doubts here!
And the video too.

 

[Spirit95]

what is the difference between stretch and enlargement?

Let us forget invariant lines for a while. Enlargement is when the whole object changed its size. Stretch changes the size of one side of the object, while the other one stays the same. For example, if a square with sides 2cm is enlarged by the scale factor of 2, then the square will become larger with sides of 4cm. However, if this square of 2cm is stretch horizontally by the scale factor of 2, then the horizontal sides will become 4cm, while the vertical ones remain 2cm, changing the square into a rectangle.

 

[Ahmed Khider]

In question paper 43 oct-nov 2011 i couldnt do questions 1 & 5a please help

 

[ktc]

In question paper 43 oct-nov 2011 i couldnt do questions 1 & 5a please help

For question 1:

a] You have to find the volume of water, in the rectangular tank, first:
0.5xo.8x1.2 = 0.48m3

Now, 0.3m3 of water flows from the full tank into the cylinder in 1 minute:-

0.3m3-> 1minute
0.48m3-> x minutes

Therefore x = 1.6 minutes which => 1 minute and 36 seconds.

b] The volume of the cylinder is given by the equation -> πr2h

πr2h = 0.48m3 [all the water from the tank drained into the cylinder]
π (0.4)2(h) = 0.48
So, h = 0.95m.

c] [Inner] surface area = πr2 + 2πrh
= [π (0.4)2] + [2 π(0.4) (1.2)]
= 3.52m2 (rounded it to 3 significant figures)

Since, 1m2 -> $2.30
3.52m2-> x
Therefore x = $8.09

As for question 5

a] let’s say the cost of a bottle of water = x cents
Thereby, the cost of a bottle of juice = x+5 cents

Since the guy bought 3 bottles of water and 6 bottles of juice and ended up paying $5.25.

The equation would be -> 3x + 6(x+5) = 525 (cents)
X = 55 cents.

[just felt like making it colorful ]

 

[Ahmed Khider]

For question 1:

a] You have to find the volume of water, in the rectangular tank, first:
0.5xo.8x1.2 = 0.48m3

Now, 0.3m3 of water flows from the full tank into the cylinder in 1 minute:-

0.3m3-> 1minute
0.48m3-> x minutes

Therefore x = 1.6 minutes which => 1 minute and 36 seconds.

b] The volume of the cylinder is given by the equation -> πr2h

πr2h = 0.48m3 [all the water from the tank drained into the cylinder]
π (0.4)2(h) = 0.48
So, h = 0.95m.

c] [Inner] surface area = πr2 + 2πrh
= [π (0.4)2] + [2 π(0.4) (1.2)]
= 3.52m2 (rounded it to 3 significant figures)

Since, 1m2 -> $2.30
3.52m2-> x
Therefore x = $8.09

As for question 5

a] let’s say the cost of a bottle of water = x cents
Thereby, the cost of a bottle of juice = x+5 cents

Since the guy bought 3 bottles of water and 6 bottles of juice and ended up paying $5.25.

The equation would be -> 3x + 6(x+5) = 525 (cents)
X = 55 cents.

[just felt like making it colorful ]

Thank you verrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrry much. As for question 5(a) i thought it would a lot more complicated since it is for 4 marks!!!!!!!!!!!!!!!. Btw could you solve question 5(b)? Once again thanks alot .

 

[ktc]

No problem!

5 b]

The cost of a biscuit = x cents.
The total cost of the biscuits = 72 cents.
Therefore, the total number of biscuits bought = 72/x

The cost of a cake = x+3 cents
The total cost of the cakes = 72 cents
Therefore, the total number of cakes bought = 72/x+3

Now, the total number of biscuits bought is 2 more than the total number of cakes bought for 72 cents.

Therefore, the equation would be -> 72/x = 2 + [72/x+3]
= 72/x = [2x + 6 + 72]/x+3
= 72[x+3] = x [2x + 78x]
= 72x + 216 = 2x2 + 78x
= 72x – 78x + 216 – 2x2 = 0
= -6x + 216 - 2x2 = 0
= - 3x + 108 + x2 = 0
= 3x – 108 + x2 = 0

Hence, x2 + 3x – 108 = 0

And yeah, marks can be deceiving

 

[hredoymohammad]

anyone help me ..how to express N in terms of it.....lgN = 4lgt-0.6 ...O/N 2011 p-11 ques 3ii)

answer given is N=.251 t^4 but how do u reach dis..?

 

[CaptainDanger]

anyone help me ..how to express N in terms of it.....lgN = 4lgt-0.6 ...O/N 2011 p-11 ques 3ii)

answer given is N=.251 t^4 but how do u reach dis..?

Link to paper?

 

[hredoymohammad]

Link to paper?

http://www.mediafire.com/download.php?dc1339weg11ihib

also q 11 (OR) Hence show that r =
10 sin θ
1 + sin θ .

i dont get the mark scheme...the sin theta value is wrong?

 

[ICCWC2015]

During the exam, in paper 2 do we have to solve the question on a rough paper and write the answer in the space given for answers OR
Do we have to solve the question on the paper itself..Like Q1 of this paper
http://www.xtremepapers.com/CIE/Cambridge IGCSE/0580 - Mathematics/0580_s11_qp_21.pdf

 

[Spirit95]

During the exam, in paper 2 do we have to solve the question on a rough paper and write the answer in the space given for answers OR
Do we have to solve the question on the paper itself..Like Q1 of this paper
http://www.xtremepapers.com/CIE/Cambridge IGCSE/0580 - Mathematics/0580_s11_qp_21.pdf

In P2, working out the answers are always shown on the paper itself. No extra papers are provided, except for tracing paper, which is not useful in this case.

 

[hredoymohammad]

http://www.xtremepapers.com/CIE/Cambridge O Levels/4024 - Mathematics/4024_w10_qp_22.pdf ...can anyone help me with no 10(iv) a...i have done upto (a b) (0 1 0) = (0 2 0) but den wat?? i can find it out if it was 2 * 2 matrix...but how to deal with
c d ... 0 0 1 .... 0 0 3.......................................................................................................................
2*3 matrix n in iv(b) y it is not enlargement??? n how do we know if its enlargement or stretch?

 

[hredoymohammad]

n also question 10...how to do dis..its not on a graph? :O

 

[Iridescent]

Its rotation 180 degrees and the centre will be the mid-point of the line RS. It won't be on a graph.