Maths, Addmaths and Statistics: Post your doubts here!

[Bivek]

Pls guys help me, how to get c (y-intercepy}............ thanx....!!!
ans-:lgc=-o.6
c=0.251

 

[Ram97]

Pls guys help me, how to get c (y-intercepy}............ thanx....!!!
ans-:lgc=-o.6
c=0.251

EASY

1. First take out the gradient which is "4" which is the value of m.
2. Put the gradient in the equation and the values of x that is (lg t) and y that is (lg N) and you will automatically find lg c (Equation=3.4=4(1)-lg c)
3. lg=10^x (x=unknown) so lg c (-0.6) is equals 10^-0.6
4. Find the value of (10^-0.6) and that is the value of c.

If any doubt in understanding then post it on my wall.

 

[Mohammad Farzanullah]

PLZ HELP:


When illustrating the use of moving averages, three students F, G and H, carry out the following
calculations.
F Four-quarter moving averages on the quarterly electricity consumption of a particular
household.
G Seven-year moving averages on annual sales figures for a clothing manufacturer.
H Twelve-month moving averages on the monthly rainfall at a particular location.
(i) For each of the three students, state whether or not it is necessary to centre these moving
averages. In each case give a brief reason. [3]
(ii) For each of the three students, state what kind of variation the student is attempting to
eliminate by calculating the moving averages.

(N2002/p2/q6)

 

[Haris Bin Zahid]

Anyone please solve the following question:
2 cot 2x=5 for 0<=x<=360
I'm getting only two answers, whereas the Redspot Classified book gives four answers.
scouserlfc: Your help will be highly appreciated.

 

[zainab]

Can somebody please solve stats nov 2011 paper 12, Q7 part (iv)?
My answer does not match with the one in examiner report. Please help!

 

[Cambridge Stud]

Anyone please solve the following question:
2 cot 2x=5 for 0<=x<=360
I'm getting only two answers, whereas the Redspot Classified book gives four answers.
scouserlfc: Your help will be highly appreciated.

2 cot 2x = 5
2(cos 2x/sin 2x) = 5
use compound angle formulae for cos 2x = 1-2 sin^2 x
and sin 2x = 2 sin x cos x
replace in equation and after simplifying, you'll get
2 - 4 sin^2 x = 10 sin x cos x
2 sin^2 x + 5 sin x cos x = 1
sin x (2 sin x + 5 cos x) = 1
either sin x = 1 (look for sin^-1)
or 2 sin x + 5 cos x = 1 (divide by cos x to obtain equation in tan x and solve)

hope it's good

 

[Mustafa Malik]

Hey any1 has guess for math 4024 oct 2012??

 

[Haris Bin Zahid]

2 cot 2x = 5
2(cos 2x/sin 2x) = 5
use compound angle formulae for cos 2x = 1-2 sin^2 x
and sin 2x = 2 sin x cos x
replace in equation and after simplifying, you'll get
2 - 4 sin^2 x = 10 sin x cos x
2 sin^2 x + 5 sin x cos x = 1
sin x (2 sin x + 5 cos x) = 1
either sin x = 1 (look for sin^-1)
or 2 sin x + 5 cos x = 1 (divide by cos x to obtain equation in tan x and solve)

hope it's good

Thanks for your help, but I'm afraid that it's wrong.
By the way I solved it on my own.

 

[ayesha1429]

Notes on histograms ? Pleasee ? :s

 

[ayesha1429]

Guys i need help.. Theres this question about histogram in which x-axis shows the masses of parcels from 1-8.. the intervals of all classes is 1... y axis shows the frequency(no. of parcels..)
and the question is : FInd a calculated estimate of the number of parcels with masses of 5.5 or more ..
Please help :s

 

[Aina]

i need paxt paper of statistics of 2011 and 2010 plxx help me

 

[scouserlfc]

Anyone please solve the following question:
2 cot 2x=5 for 0<=x<=360
I'm getting only two answers, whereas the Redspot Classified book gives four answers.
scouserlfc: Your help will be highly appreciated.

Have u tried using the tan2x identity after converting cot2x to 1/tan2x because that would form a quadratic equation and u should get 2 answers
And also how did u do it urself ????

 

[Haris Bin Zahid]

Have u tried using the tan2x identity after converting cot2x to 1/tan2x because that would form a quadratic equation and u should get 2 answers
And also how did u do it urself ????

Yeah I rearranged the equation into tan 2x = 0.4.....used the tan2x identity and derived the four answers: 10.9, 100.9, 190.9 and 280.9.

 

[huzaifa khanani 123]

according to paper one, now what is expected in paper two? (if this question is legal to ask here) and
my question is that whenever the entry fees in a game is given, do we have to subtract the prize from the entry fees in order to calculate the expected profit or loss or not?

 

[kainat husain]

PLEASE HELP!
mensuration
1- a golf ball of diameter 1.68 inches rolls a distance of 4m in a straight line , how many times does the ball rotate completely ?
(1 inch= 2.54 cm)
ans- 29
how to do this to get d answer? :/
2- an archery target has three concentric regions. The diameters of the regions are in the ratio 1:2:3. find the ratios of their areas
ans- 1:3:5
but how?
3- mrs. gibson decided to build a garage and began by calculating the number of bricks required. the garage was to be 6m by 4m and 2.5m in height. each brick measures 22 cm by 10 cm by 7cm. mrs gibson estimated that she would need about 40,000 bricks. is this a reasonable estimate?
the ans is no but how?
4- a circukar paper of radius 20cm is cut in half and each half is made into a hollow cone by joining the straight edges. find the slant height and base radius of each cone
ans- 20cm, 10cm.
5- a golf ball has a diameter of 4.1cm and the surface has 150 dimples of radius 2mm. Calculate the total surface area which is exposed to the surroundings. (assume the dimples are hemispherical)
ans-71.7cm^2 but pls tell how to do
6- a cone of radius 3cm and slant height 6cm is cut into for identical pieces. calculate the total surface area of the four pieces.
ans-147cm^2
pleeaseeeeeeeeeeeeeeeeeeeeeee help
TMW IS MY EXAM

 

[marshall mathers]

Guys what about this one 8siny+ 3 secy=0. Can you solve it without using 2sinxcosx= sin2x???

 

[marshall mathers]

Re: O'level Maths, Addmaths and Statistics help available he

Can someone solve this question for me?

Two ships, A and B, leave their ports simultaneously at 12 00 hours. The ports are 104 km apart with one port due west of the other. The speeds and directions of the two ships are shown in the diagram, where tan x = 3/4 and tan y = 12/5. Find:

a) The speed and direction of the velocity of A relative to B;
b) The time at which A is due south of B and the distance between A and B at this instant;
c) The distance between the two ships at 17 00 hours.

Thanks in advance!

You need to specify which one is angle x and which one is angle y. Is x the angle for A or the angle for B??

 

[Minato112]

Guys what about this one 8siny+ 3 secy=0. Can you solve it without using 2sinxcosx= sin2x???

Convert the sec x into 1/cos x and solve.

 

[marshall mathers]

You need to specify which one is angle x and which one is angle y. Is x the angle for A or the angle for B??

If x is the angle at A, you draw a quadrant, evaluate x. Then draw a line with an angle x to the horizontal. This shows the direction in which A is moving. Now using the velocity of A(which you forgot to specify) find this velocity in vector form. To do this find the horizontal displacement which will be given by Va multiplied by cos x and the vertical displacement Va multiplied by sin x. In this case the angle is acute so you draw your line representing Va in the first quadrant. Repeat the same procedure for Vb then the answer to your first part will be Va-Vb in IN VECTOR FORM. Then to obtain the CORRECT ANSWER you evaluate the magnitude of this vector. It's pretty damn difficult to explain on the net but i tried my best in explaining the first part as the other parts need to be demonstrated so that you fully understand. If you didn't understand it then try checking on youtube. This method is known as the resolution of vectors. Sorry mate but i tried my best

 

[marshall mathers]

Convert the sec x into 1/cos x and solve.

Yeah but you'll be getting 8sinycosy=-3. So can you solve that WITHOUT USING any double angle identities???