• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Mathematics: Post your doubts here!

Messages
21
Reaction score
17
Points
13
HELP
A committee of 5 people is to be chosen from 6 men and 4 women. In how many ways can this be done
(iii) if there must be 3 men and 2 women, and one particular woman refuses to be on the committee with one particular man?
 
Messages
924
Reaction score
1,096
Points
153
Messages
1,824
Reaction score
5,326
Points
523
v1 = 0.02t + 1

v1 - v = 0.02t+1 - (0.04t − 0.000 05t^2)
= 0.02t + 1 - 0.04t + 0.00005t^2
= 0.00005t^2 - 0.02t + 1
= 0.00005(t^2 - 400t + 20000)
= 0.00005[t^2 - 400t + 200^2 - 200^2 + 20000]
= 0.00005[(t - 200)^2 - 20000]
= 0.00005(t - 200)^2 - 1
Thnx for replying...........but I dont get the v1, how did u find it?
:)
 
Messages
924
Reaction score
1,096
Points
153
Thnx for replying...........but I dont get the v1, how did u find it?
:)
v1 is the first part of the graph. So we simply need it's equation.
gradient = (9-1)/(400-0) = 0.02
y - intercept = 1
So v1 = 0.02t + 1

Or alternatively,
v = u+at,
Where u=1, a=0.02
v1 = 1 + 0.02t
 

Attachments

  • QuickMemo+_2015-09-29-21-38-02.png
    QuickMemo+_2015-09-29-21-38-02.png
    60.4 KB · Views: 3
Messages
1,824
Reaction score
5,326
Points
523
v1 is the first part of the graph. So we simply need it's equation.
gradient = (9-1)/(400-0) = 0.02
y - intercept = 1
So v1 = 0.02t + 1

Or alternatively,
v = u+at,
Where u=1, a=0.02
v1 = 1 + 0.02t
Thanku sooo much!!
God, it was that easy.................. I feel dumb! :D
 
Messages
69
Reaction score
48
Points
28
(i) f(x) = 4, so: 6 - 4cos(0.5x) = 4
cos(0.5x) = 0.5
0.5x = π / 3 (since it says exact, no need for basic angles and stuff)
x = 2π / 3

(ii) Max = a + b = 6+4 = 10 and Min = a - b = 6 - 4 = 2
So, range: 2 <f(x)<10

(iii) The graph is going to be upside down since the cos is -ve.............. so it would be something like this: (sorry for the crappy drawing though)
View attachment 57098

(iv) The inverse is just like the normal one

Hope it helps............... :)
Sorry for the late reply. Could you explain how did you get the exact value of the inverse of cos 0.5?
 
Messages
924
Reaction score
1,096
Points
153
Sorry for the late reply. Could you explain how did you get the exact value of the inverse of cos 0.5?
These are the common angles and their trigonometric ratios you should try to learn:

6965817_f520.jpg


As you can see, cos^-1(0.5) = 60°, or π/3 radians.
 
Messages
69
Reaction score
48
Points
28
(i) f(x) = 4, so: 6 - 4cos(0.5x) = 4
cos(0.5x) = 0.5
0.5x = π / 3 (since it says exact, no need for basic angles and stuff)
x = 2π / 3

(ii) Max = a + b = 6+4 = 10 and Min = a - b = 6 - 4 = 2
So, range: 2 <f(x)<10

(iii) The graph is going to be upside down since the cos is -ve.............. so it would be something like this: (sorry for the crappy drawing though)
View attachment 57098

(iv) The inverse is just like the normal one

Hope it helps............... :)
Yeah I understood it. Thanks a lot for your help!
 
Messages
69
Reaction score
82
Points
28
A small doubt..
According to grade threshold of 2015
To get A we should get at least 62 in paper 1 and 42 in paper 6
So my doubt is In paper 1 I scored 68 and in paper 6 I scored 30.
What will be my grade?? C or B or A ?
 
Top