MSB47
Badges: 2
Rep:
?
#1
Report Thread starter 6 years ago
#1
question 1 (b) where it talks about the percentage diiference I am just wondering what expression to use when calculating the percentage difference for n number of paper clips which im assuming is derived fron L= nc - 2d (n-1).

the mark scheme mentions about the expression to use for calculating percentage difference - 100 x ( 2d/c - 2d/nc) not sure how they achieved that?

Posted from TSR Mobile
Attached files
0
reply
Phichi
Badges: 11
Rep:
?
#2
Report 6 years ago
#2
Off the top of my head the most logical way of thinking about it would be this:

The student suggests that L \approx nc, thus \dfrac{L}{nc} \approx 1

100\dfrac{L}{nc} represents the percentage, i.e, if nc = 1.2m and L = 1m, nc is 120% L. I'm assuming that nc \geq L, as from the equation, L is equal to nc minus some value.

From the equation:

\dfrac{L}{nc} = 1 - \dfrac{2d}{nc}(n-1)

Converting this into a percentage as before:

100\dfrac{L}{nc} = 100 - \dfrac{100(2d)}{nc}(n-1)

From this it is clear that \dfrac{100(2d)}{nc}(n-1) is the percentage difference.

If this isn't clear to you, if the percentage difference was 0, then we would have L = nc, or \dfrac{L}{nc} = 1 \, \, \, \Rightarrow \, \, \, 100\dfrac{L}{nc} = 100

The percentage difference being 0 infers \dfrac{100(2d)}{nc}(n-1) = 0

Remember \dfrac{100(2d)}{nc}(n-1) \equiv 100 \times \left(\dfrac{2d}{c} - \dfrac{2d}{nc}\right) as you posted, to avoid any confusion.
0
reply
MSB47
Badges: 2
Rep:
?
#3
Report Thread starter 6 years ago
#3
(Original post by Phichi)
Off the top of my head the most logical way of thinking about it would be this:

The student suggests that L \approx nc, thus \dfrac{L}{nc} \approx 1

100\dfrac{L}{nc} represents the percentage, i.e, if nc = 1.2m and L = 1m, nc is 120% L. I'm assuming that nc \geq L, as from the equation, L is equal to nc minus some value.

From the equation:

\dfrac{L}{nc} = 1 - \dfrac{2d}{nc}(n-1)

Converting this into a percentage as before:

100\dfrac{L}{nc} = 100 - \dfrac{100(2d)}{nc}(n-1)

From this it is clear that \dfrac{100(2d)}{nc}(n-1) is the percentage difference.

If this isn't clear to you, if the percentage difference was 0, then we would have L = nc, or \dfrac{L}{nc} = 1 \, \, \, \Rightarrow \, \, \, 100\dfrac{L}{nc} = 100

The percentage difference being 0 infers \dfrac{100(2d)}{nc}(n-1) = 0

Remember \dfrac{100(2d)}{nc}(n-1) \equiv 100 \times \left(\dfrac{2d}{c} - \dfrac{2d}{nc}\right) as you posted, to avoid any confusion.
That makes sense, thanks a lot for your help
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Poll: What factors affect your mental health most right now? Post-lockdown edition

Anxiousness about restrictions easing (29)
5.68%
Uncertainty around my education (59)
11.55%
Uncertainty around my future career prospects (61)
11.94%
Lack of purpose or motivation (66)
12.92%
Lack of support system (eg. teachers, counsellors, delays in care) (28)
5.48%
Impact lockdown had on physical health (23)
4.5%
Social worries (incl. loneliness/making friends) (53)
10.37%
Financial worries (31)
6.07%
Concern about myself or my loves ones getting/having been ill (20)
3.91%
Exposure to negative news/social media (32)
6.26%
Difficulty accessing real life entertainment (15)
2.94%
Lack of confidence in making big life decisions (51)
9.98%
Worry about missed opportunities during the pandemic (43)
8.41%

Watched Threads

View All
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise