Maths, Addmaths and Statistics: Post your doubts here!

[Hamza Malik 123]

hey guys plz help im very much confused in probabaility i cannot figure out weather it is with or without replacement

 

[SiriusA]

hey guys plz help im very much confused in probabaility i cannot figure out weather it is with or without replacement

It is just the book questions that are confusing. Otherwise in CIE, it usually mentions whether it is with or without replacement.

As a thumb rule, keep this in mind :

All questions of Probability in CIE are without replacement until it is mentioned. One exception however, is if candies are eaten, if candies eaten is the case surrounding, then it makes common sense that a toffee eaten can not be replaced automatically.

Check out the past papers, it always mention "with" or "without replacement".

 

[Hamza Malik 123]

Thanku SiriusA but wat abt the question in which it is said 2 children are chosen at random

 

[Yahyasm]

Help needed
Rizwan Javed

 

[Rizwan Javed]

Hope I'm not late.

Consider the above triangle i have drawn. Here:
V l/s means velocity of life boat relative to ship
V s means velocity of ship
V l means velocity of life boat.

The horizontal distance between ship and life boat is 30km at 1500. since we're given time of interception which is (1540 - 1500) = 40 min = 0.67 hours, so we can calculate the value for V l/s by
V l/s = d/t = 30/0.67 = 45 km/h <-- the value i wrote on diagram was calculated this way.

So simply apply cosine rule on this vector triangle to calculate the value for V l.

V l ^2 = 45^2 + 15 ^ 2 - 2(45)(15)cos (60°)
V l = 39.7 km/h <-- Ans.

If you have any ambiguity in this solution feel free to ask me.

 

[Yahyasm]

Hope I'm not late.
View attachment 57371
Consider the above triangle i have drawn. Here:
V l/s means velocity of life boat relative to ship
V s means velocity of ship
V l means velocity of life boat.

The horizontal distance between ship and life boat is 30km at 1500. since we're given time of interception which is (1540 - 1500) = 40 min = 0.67 hours, so we can calculate the value for V l/s by
V l/s = d/t = 30/0.67 = 45 km/h <-- the value i wrote on diagram was calculated this way.

So simply apply cosine rule on this vector triangle to calculate the value for V l.

V l ^2 = 45^2 + 15 ^ 2 - 2(45)(15)cos (60°)
V l = 39.7 km/h <-- Ans.

If you have any ambiguity in this solution feel free to ask me.

U know it says 270 bearing i dont get that part really and have a strange shape, instead i have the 45km at other side

 

[Rizwan Javed]

i have already placed the ship at 270 bearing with respect to life boat.
The green circle shows the position of life boat at 1500 and red circle shows the position of ship at 1500. So to intercept the ship, the life boat moves in the direction of V l to intercept the ship as ship s moving at bearing of 150 or at 60 degree to horizontal.

The life boat and ship meet at the point where heads of V s and Vl vectors meet.

Still any confusion? and i didn't get how you got 45 km? can you plz post your diagram?

 

[Yahyasm]

View attachment 57372
i have already placed the ship at 270 bearing with respect to life boat.
The green circle shows the position of life boat at 1500 and red circle shows the position of ship at 1500. So to intercept the ship, the life boat moves in the direction of V l to intercept the ship as ship s moving at bearing of 150 or at 60 degree to horizontal.

The life boat and ship meet at the point where heads of V s and Vl vectors meet.

Still any confusion? and i didn't get how you got 45 km? can you plz post your diagram?

Thx bro got it...

 

[Yahyasm]

Rizwan Javed plz come to my aid......

 

[Yahyasm]

Which area does integration of curve x2 -6x +10 represent for x (0 till 7) .

 

[Rizwan Javed]

Rizwan Javed plz come to my aid......

y = x^2 -6x + 10 ---- (1)
y = x + 10 --- (2)

solving (1) & (2)
x + 10 = x ^2 -6x +10

0 = x^ 2 - 7x
x(x - 7) = 0
either
x = 0 or x = 7
putting these coordinates in (2) to find the y-coordinates of these two points:
y = 0+10
= 10
y = 7 +10
= 17
so,
A (0, 10)
B (7, 17)

area of shaded region = area of trapezium AOCB - Area under the curve from x = 0 t0 7
= (1/2 (10 +17) * 7) - ∫ (x^2 -6x +10) dx

= 94.5 - 112/3
= 343/6 sq. units <---shaded area

This was the question i solved in my CIE paper

 

[Rizwan Javed]

Which area does integration of curve x2 -6x +10 represent for x (0 till 7) .

The region marked 3.

 

[Yahyasm]

Ok thankew, idk why I thought it represented 1 and 2, just a silly mistake from me. I owe u big time.....

 

[husnain99]

Can someone please solve both of these parts ? Thanks

 

[cool.fireboy24]

I think in the first part they say that 90% is added in original price... but for employees it is 20% disscount so we can minus that.. And as the employee is paying $80 for it so we can take 70% of it............... and add it... because it is said that cost price has 90% added to it which in this case will be 70... after that % profit will be taken out by dividing 80 with the new price taken out and multiplyed by 100..................
I think its the way to solve it.. its going to be incorrect i guess
B part is like we can do the 35% of the price given ......... and i can be calculated after this......

Where is this question from.. Commercial Studies??????????

 

[Yahyasm]

I think in the first part they say that 90% is added in original price... but for employees it is 20% disscount so we can minus that.. And as the employee is paying $80 for it so we can take 70% of it............... and add it... because it is said that cost price has 90% added to it which in this case will be 70... after that % profit will be taken out by dividing 80 with the new price taken out and multiplyed by 100..................
I think its the way to solve it.. its going to be incorrect i guess
B part is like we can do the 35% of the price given ......... and i can be calculated after this......

Where is this question from.. Commercial Studies??????????

i think cp is given $80 so for normal people the sale price(sp) will be 1.9X80=152
however employees have 20% disc. so they pay 80% only hence 0.8X152=121.6
profit=121.6-80=41.6
41.6/80 X100% =52%
and
let cp be x
sp=1.9x
e.p=1.9x X 0.8=1.52x
seasonal bla bla = 0.85 X 1.52x = 1.292x
so on season he paid 64.6
therefore
64.6=1.292x
x=64.6/1.292
x=50

 

[husnain99]

i think cp is given $80 so for normal people the sale price(sp) will be 1.9X80=152
however employees have 20% disc. so they pay 80% only hence 0.8X152=121.6
profit=121.6-80=41.6
41.6/80 X100% =52%
and
let cp be x
sp=1.9x
e.p=1.9x X 0.8=1.52x
seasonal bla bla = 0.85 X 1.52x = 1.292x
so on season he paid 64.6
therefore
64.6=1.292x
x=64.6/1.292
x=50

Yeah thanks !
( same answers in the Ms )

 

[cool.fireboy24]

i think cp is given $80 so for normal people the sale price(sp) will be 1.9X80=152
however employees have 20% disc. so they pay 80% only hence 0.8X152=121.6
profit=121.6-80=41.6
41.6/80 X100% =52%
and
let cp be x
sp=1.9x
e.p=1.9x X 0.8=1.52x
seasonal bla bla = 0.85 X 1.52x = 1.292x
so on season he paid 64.6
therefore
64.6=1.292x
x=64.6/1.292
x=50

Yeah i realized 3 mins after i posted...

 

[Yahyasm]

Yeah thanks !
( same answers in the Ms )

are these qs from d maths past papers

 

[smiling star]

Hii guys,can anyone of you share the notes of graphs of tangent functions of addmath pls?