maths question help please
hi, please could I have some help on part b of this question? I thought that one sd away from the mean occupies 33% area, so i estimated the mean to be 164, indicated by the peak and one 33% away was roughly at 178 so the sd would be 14 but this is wrong?
question: https://ibb.co/nsKD0cLS
thanks!
question: https://ibb.co/nsKD0cLS
thanks!
Reply 1
21
Original post
by anonymous56754hi, please could I have some help on part b of this question? I thought that one sd away from the mean occupies 33% area, so i estimated the mean to be 164, indicated by the peak and one 33% away was roughly at 178 so the sd would be 14 but this is wrong?
question: https://ibb.co/nsKD0cLS
thanks!
question: https://ibb.co/nsKD0cLS
thanks!
What you say is ok, but the 33% being 178 looks way too large. Why that number?
You could say the (visual) range was ~6 std devs or the point(s) of inflection are 1 std dev from the mean or ...
Reply 2
33% away was roughly at 178 ?? I'm not sure how you reached such conclusion.
33% of 3 standard deviations? it's just one standard deviation
Why do you think about mean that it occupies area?
area is flat, or two-dimensional,
distance, variance, between two values (on the same axis, if there are no units mentioned) is linear, one-dimensional
From graph, you can derive:
mean, ~163.5, I think both 163, and 164 would be correct answers
95% of data points falls between ~145, and ~182,
so 145 is 3 standard deviation lower than mean, and 182 is 3 standard deviation higher than mean,
that gives standard deviation ~(163-145)/3=~6
33% of 3 standard deviations? it's just one standard deviation
Why do you think about mean that it occupies area?
area is flat, or two-dimensional,
distance, variance, between two values (on the same axis, if there are no units mentioned) is linear, one-dimensional
From graph, you can derive:
mean, ~163.5, I think both 163, and 164 would be correct answers
95% of data points falls between ~145, and ~182,
so 145 is 3 standard deviation lower than mean, and 182 is 3 standard deviation higher than mean,
that gives standard deviation ~(163-145)/3=~6
Reply 3
21
Original post
by M.W.Shayboski33% away was roughly at 178 ?? I'm not sure how you reached such conclusion.
33% of 3 standard deviations? it's just one standard deviation
Why do you think about mean that it occupies area?
area is flat, or two-dimensional,
distance, variance, between two values (on the same axis, if there are no units mentioned) is linear, one-dimensional
From graph, you can derive:
mean, ~163.5, I think both 163, and 164 would be correct answers
95% of data points falls between ~145, and ~182,
so 145 is 3 standard deviation lower than mean, and 182 is 3 standard deviation higher than mean,
that gives standard deviation ~(163-145)/3=~6
33% of 3 standard deviations? it's just one standard deviation
Why do you think about mean that it occupies area?
area is flat, or two-dimensional,
distance, variance, between two values (on the same axis, if there are no units mentioned) is linear, one-dimensional
From graph, you can derive:
mean, ~163.5, I think both 163, and 164 would be correct answers
95% of data points falls between ~145, and ~182,
so 145 is 3 standard deviation lower than mean, and 182 is 3 standard deviation higher than mean,
that gives standard deviation ~(163-145)/3=~6
Pretty much, though the +/-3 std dev corresponds to ~99.7% of the data and +/-2 std dev corresponds to ~95%. Going down those routes, just get max-min (range) and divide by 6 or 4.
(edited 10 months ago)
Quick Reply
Related discussions
- Pharmacy interview in wolverhampton
- Requesting advice on good online resources for AS Maths
- Gcse maths higher aqa
- A-Level Maths Help!!
- Exeter for maths with econ or nottingham for econ with international econ?
- UCL UPC Interview
- advice needed!!!
- Year 11 GYG- Can we lock in?
- Gcse resit
- Seven king students help me
- GCSE Mathematics Study Group 2024-25
- a level maths
- How to Find Challenging Maths Questions + Revision Tips
- How to go from a 5 to 7 in gcse maths in 4 months ?????
- BSc Accounting & Finance or BSc Financial Maths?
- How to improve maths alevel
- Maths in Electrical and electronic engineering at sheffield
- Alevel comeback possible???
- 2025-26 Higher Maths discussion
- Oxbridge Maths Interviews - how do you prepare?
Latest
Trending
Last reply 6 months ago
Methods of rationalisation of denominators of complex numberLast reply 6 months ago
Which A-level Maths/Further Maths topics gave you the most trouble?Posted 7 months ago
Pls help me pls im acc gonna die pls pls help me AS EDEXCEL MATHSLast reply 7 months ago
Grade Boundaries Edexcel Further Maths 3A 3C (FP1 & FM1)Last reply 7 months ago
Edexcel AS Level Maths May 15th 2025 Pure Paper 1 + Unofficial Mark SchemeMaths Study Help
67
160
Articles for you
How The Student Room is moderated
To keep The Student Room safe for everyone, we moderate posts that are added to the site.
