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Mathematics: Post your doubts here!

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still don't understand...can u solve it on paper and send photo plz?explain the other question also

In the first part (for 36 values)
Σ(x − 45) = −148 and
Σ(x − 45)^2=3089

Now for finding sd of 37 values we need new Σ(x − 45) and Σ(x − 45)^2
x=29

(x-45)=29-45=-16
so new Σ(x − 45)= -148+(-16)=-164

(x-45)2=(29-45)^2=256
So new Σ(x − 45)^2 =256+3089=3345

now you got new values of Σ(x − 45) and Σ(x − 45)^2
so just apply the formula of sd to get the answer

Hope you got it
 
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intervals for what? :confused:
the frequencies? the weights?
let me tell you what i do
for example Q6(iii)
For the weight which is x
add first with the second /2 and so on
so here (40+50)/2, (50+60)/2 , ...................<---x values
now for the frequencies
the second- first
so here
(12-0),(34-12).................
and then i use the equation in the data booklet mean= sum of fx /f
 
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Weight (x kilograms) for the (first paper)
Mark (for the second paper)
Number of pupils in a school (for third paper)
 
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Weight (x kilograms) for the (first paper)
Mark (for the second paper)
Number of pupils in a school (for third paper)
For the weight which is x
add first with the second /2 and so on
so here (40+50)/2, (50+60)/2 , ...................<---x values

and then i use the equation in the data booklet mean= sum of fx /f
for the first paper
for second
(10+20)/2 , (20+35)/2..........
for the third
100+150/2, 150+200/2 and so on
this is how i get x values
 
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In the first part (for 36 values)
Σ(x − 45) = −148 and
Σ(x − 45)^2=3089

Now for finding sd of 37 values we need new Σ(x − 45) and Σ(x − 45)^2
x=29

(x-45)=29-45=-16
so new Σ(x − 45)= -148+(-16)=-164

(x-45)2=(29-45)^2=256
So new Σ(x − 45)^2 =256+3089=3345

now you got new values of Σ(x − 45) and Σ(x − 45)^2
so just apply the formula of sd to get the answer

Hope you got it
great....thnx....and explain also the other question of combination
 
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u=cosx
du/dx= -sinx
dx= -du/sinx
change limits
if u =cosx
and x=pi/2
uper limit u=o
x=0
lower limit u=cos0=1
integrate
5sin^3 cos^2 * -du/ sin
cancelling sin
-5sin^2 cos^2 du
remember that 1-cos^2=sin^2
-5(1-cos^2)(cos^2) du
-5(1-u^2)(u^2)
-5(u^2 -u^4)
now integrate for0 to 1
-5( u^3)/3 +5(u^5)/5 put 0 to 1
0-(-5( u^3)/3 +5(u^5)/5 )
2/3 :/ wats the ans
Lostsoul
 
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