Maths Paper 4 Discussion

[Ahsen420]

Could we discuss the last question Part (c) and (d)

 

[Aahmsil]

Impossible

Not before 24 hours I guess !!!

Cheers !!! :good:

 

[Adahshan]

Easy

C was a formula 2^n-1 and d was 0.5 and 1.5

 

[Ahsen420]

What is formula for the nth term of the sequencefirst 5 given below)
1 2 4 8 16

 

[Dooouuu]

Easy

C was a formula 2^n-1 and d was 0.5 and 1.5

are u sure from d ?

 

[Violettamee]

and yeah .... there was one more question in the maths paper bout finding the frustum of the cone ...
anyone remembers?????? the questions on mensuration ...: there was this question where u needed to find the height/volume/area bla bla bla of the cone ????????? and the last question says something like this :-
this is the same cone as in part (c) with its top cut off... find the volume of the cone.." i donno it was SOMETHING like that .. u just needed to find the volume of the lower part of the cut-off cone.... :\ :\ :\

anyway any1 knows how u had to solve that ?????????????????????????

 

[DarkMeridian]

Its not been 24 hours yet, this discussion is against the rules. I'll edit my answer for your question Violettamee once the 24 hours are up. Which is in about 3.5 hours.

EDIT: You divide the volume of the cone in the previous part by two. Then you simply subtract the volume of the whole cone by the smaller cone!

 

[SmartNour]

Guys please tell me about the mensuration part...I really need to know if am wrong :unknown:

 

[mido4help]

The dotted cone (above one) is similar to bigger cone which is dotted cone is inside it. Then calcuate the volume ratio between slant heights and the bring the volume of dotted cone. At end subtract the volume o dotted cone rom large cone.
This was totally indirect question.
About height it's only applying Pythagoras therom
And radius it's brought by rule o curved(lateral) area

 

[adigamerboy]

I think that the answer to the volume of that remaining cone was 70 or 71 or something like that. you had to use similarity to get it.

 

[mido4help]

also this is my answer

 

[SonalDhanturi]

Yeah, i guess i messed up in the mensuration question with the truncated cone.
Didn't take the ratio but i may get some carry-forward marks, hopefully.

 

[haochen]

first i used the formula givin to find the area of the small cone (radius i found by cross multiplication with slanted height)
second i fund the area of full cone then i subtract the full cone with the cuted cone to get the remaining one
hope its correct

 

[Rashu712]

and yeah .... there was one more question in the maths paper bout finding the frustum of the cone ...
anyone remembers?????? the questions on mensuration ...: there was this question where u needed to find the height/volume/area bla bla bla of the cone ????????? and the last question says something like this :-
this is the same cone as in part (c) with its top cut off... find the volume of the cone.." i donno it was SOMETHING like that .. u just needed to find the volume of the lower part of the cut-off cone.... :\ :\ :\

anyway any1 knows how u had to solve that ?????????????????????????

I didn't use the similarity rule here because I didn't think that's the way to do it lol. I didn't even learn the formula for a frustum thinking we won't get that.
So what I did was,

pi x radius x slant height = 108, as the dimensions of the cone was same as the cone before it.
pi x r x 15 = 108

I found radius by

108
----
15*pi

Using the value of the radius and the value of the slant height, I used Pythagora's theorem to get the perpendicular height of the cone.

In the diagram it was shown that 7.5 cm was the slant height of the cone that was cut off. 7.5 is half of 15, cut parallel to the base. This means that the cone cut off had half the dimensions of the original cone, as in slant height and perpendicular height halved.

So I repeated the procedure above with half the heigth and slant height, got the radius, and then found the volume of both cones using:
1/3 x pi x r^2 x height.

Subtracted the larger volume and the lower volume.

Wrote the answer.

 

[haochen]

yeah
but i did it in other waغ

 

[mido4help]

The question of angle between the rod and base
The answer was 34.2 degrees.
Also the last part the rod don't because it's lower than calcuated which was 3.02 cm
Finally can anyone his answer about interquartile
And last surface area of hexagon pyramid was about 87.2

 

[haochen]

i wrote it fit because it is higher bound (2.95) is less than calculated

 

[Adahshan]

Cone volume was 71.something..and yes im sure about the sequence.

1, 2, 4, 6, 8 SEQUENCE OR whatever was 2^n-1

 

[Aahmsil]

Sequence

Cone volume was 71.something..and yes im sure about the sequence.

1, 2, 4, 6, 8 SEQUENCE OR whatever was 2^n-1

You bet it was !!!

 

[SmartNour]

what about the pyramid with the hexagonal base ??