Mathematics: Post your doubts here!

[Wâlèé Atèéq]

dy/dx = 4 (6-2x)^-½

at x = 1, the gradient of the tangent to the curve is:
dy/dx ( at x=1 )= 4(6-2(1))^-½ = 2

gradient of normal = -1 / gradient of tangent
= -1/2

equ of normal at P,

y - 8 = -1/2 (x - 1)
2y + x = 17 -- (1)

When it cuts x-axis at Q, y=0, so x = 17

Q(17,0)

When it cuts y-axis at R, x = 0, y = 17/2
R (0, 17/2 )

mid point =( (17+0)/2 , (8.5+0)/2 ) = (17/2 , 17/4) Ans.

(b) integrate dy/dx

y = -4(6-2x)^½ +c

when x = 1, y = 8, so,

8 = -4(6-2)^½ +c
8= -4*2 + c
c = 16

so y = -4(6-2x)^½ +16

Thank-U bro.!

 

[fleurisabelle]

how do I distinguish between discrete and continuous random variables in Statistics?

 

[Anum96]

Discrete variables are always or can always be found by counting. You will always get an exact answers (Meaning no fractions ONLY whole numbers) For e.g No. of apples or No. of cars

Continuous variables are found through measurement. ALWAYS. You will get your answer in fraction (mostly) For e.g. your height or your age maybe!

 

[muhammadali233]

anyone?

 

[Anum96]

anyone?
View attachment 58739

 

[nehaoscar]

Part ii
I solved it and got the answers but in these fractions
36/60 , 18/60 , 6/60
I got 60 as I tested all possible combinations
3! = 6
if 1 is smallest then : 4C2 * 6 = 36
and same for 2 and 4 ...
and total is 5! = 60 different arrangements
So the denominator is in terms of 60
Will this be marked correct or does it need to be as denominator 10?

 

[Anum96]

View attachment 58746
View attachment 58747
Part ii
I solved it and got the answers but in these fractions
36/60 , 18/60 , 6/60
I got 60 as I tested all possible combinations
3! = 6
if 1 is smallest then : 4C2 * 6 = 36
and same for 2 and 4 ...
and total is 5! = 60 different arrangements
So the denominator is in terms of 60
Will this be marked correct or does it need to be as denominator 10?

It will be marked correct, Obviously. But it's better if you simply everything to it's lowest form. Always.

 

[nehaoscar]

It will be marked correct, Obviously. But it's better if you simply everything to it's lowest form. Always.

Usually in normal distribution tables they keep it to the total denominator
Like in the dice questions the denominator is always 36 so I thought of leaving it as 60
Also in the table, do all the denominators have to be the same? Like simplifying each answer can give different denominators for each answer...

 

[Anum96]

Usually in normal distribution tables they keep it to the total denominator
Like in the dice questions the denominator is always 36 so I thought of leaving it as 60
Also in the table, do all the denominators have to be the same? Like simplifying each answer can give different denominators for each answer...

Yes, the denominators can be different. In this question all numbers i.e. 36,18,6 and 60 are divisible by 6. That is why denominator is same. It couldve been 4/60 or 5/60 which wouldve been simplified to 1/15 and 1/12 respectively.

 

[nehaoscar]

Yes, the denominators can be different. In this question all numbers i.e. 36,18,6 and 60 are divisible by 6. That is why denominator is same. It couldve been 4/60 or 5/60 which wouldve been simplified to 1/15 and 1/12 respectively.

36/60 can also be simplifies to 3/5
So can you write in the exam 3/5, 3/10 and 1/10
Or the 3/5 has to be written as 6/10 ?

 

[Anum96]

36/60 can also be simplifies to 3/5
So can you write in the exam 3/5, 3/10 and 1/10
Or the 3/5 has to be written as 6/10 ?

Neha. All the options are correct. Some students even write down decimals but never do that since they are not exact enough in some cases.
Probability remains same whether 36/60 or 3/5 or 6/10 or 0.6

 

[nehaoscar]

Neha. All the options are correct. Some students even write down decimals but never do that since they are not exact enough in some cases.
Probability remains same whether 36/60 or 3/5 or 6/10 or 0.6

Okay thanks

 

[Anum96]

Okay thanks

Anytime!

 

[nehaoscar]

For part ii can I write that "the mean for children is greater than adults and the range for children is greater than adults" - and i have quoted the figures as well
Will I gain full marks if I write this?

 

[fleurisabelle]

View attachment 58749
View attachment 58750
For part ii can I write that "the mean for children is greater than adults and the range for children is greater than adults" - and i have quoted the figures as well
Will I gain full marks if I write this?

it seems likely that you will gain full 2 marks since you covered both points 'children's estimates more spread out' and the 'adults estimates lower' in your statement

 

[muhammadali233]

View attachment 58745

I was able to it,when i revised the similarities concept, thanks anyway

 

[fleurisabelle]

could somebody please solve any one of the questions from 13 to 16 from the image?

 

[Rizwan Javed]

could somebody please solve any one of the questions from 13 to 16 from the image?View attachment 58761

13. Integrating the expression you get:

i've put the limits in these curly braces "{ }" .

-[(cox 3x)/3 ] {π/6} {0}
= -[ cox(3(π/6))/3 - cox(3(0))/3 ]

=1/3 Ans.

 

[Educationist]

And does the answer change when we have different values on top and bottom during "cross product" ?
Can anyone pls help me solve this ?

 

[Anum96]

And does the answer change when we have different values on top and bottom during "cross product" ?
Can anyone pls help me solve this ?
View attachment 58767

I hope its clear enough. & no the answer does not change that way