How about now?(Original post by KMan_PhysCheM)
Again, kind of correct, but a) and b) have too many excess 0s.
3.14159 is itself expressed to 6sf, and 3.14000 would imply rounded to 6sf, which is wrong. 3.14 (without excess 0s) is better.
c) is completely correct.
Posted from TSR Mobile
You are Here:
Home
> Forums
>< Study Help
>< Maths, science and technology academic help
>< Maths
>< Maths Exams

Maths year 11
Announcements  Posted on  

Four things that unis think matter more than league tables  08122016 

 Follow
 1101
 20082016 11:39

 Follow
 1102
 20082016 11:43
So for the 2sf ones, a) and b) were correct before (with the zeroes), while c) had excess zeroes after the sig figs after the decimal points.
For the 3sf ones, a) and b) had too many excess zeroes (after the decimal point) but c) was correct before EDIT: c) is correct.Last edited by KMan_PhysCheM; 20082016 at 11:45. 
 Follow
 1103
 20082016 13:01
(Original post by KMan_PhysCheM)
Ahh, maybe I wasn't clear enough. We only remove excess zeroes that appear after the decimal point. 43 and 43 000 are very different numbers, while 6.2000 and 6.2 are the same number, but to different degrees of accuracy.
So for the 2sf ones, a) and b) were correct before (with the zeroes), while c) had excess zeroes after the sig figs after the decimal points.
For the 3sf ones, a) and b) had too many excess zeroes (after the decimal point) but c) was correct before EDIT: c) is correct.
Posted from TSR Mobile 
 Follow
 1104
 20082016 13:08

 Follow
 1105
 20082016 13:21
(Original post by B_9710)
These are all correct 0.05081 is 0.0.051 to 2sf and 500.6 is 501 to 3sf.
Posted from TSR Mobile 
 Follow
 1106
 20082016 13:33
Here are some bounds questions (remember, bounds are the highest and lowest numbers that would round to the given number at its given accuracy).
1) Find the upper and lower bounds of the following:
a) 350, which has been rounded to 2sf (note: 347 = 350 to 2 sf)
b) 350, which has been rounded to 3sf (note: 347 this time = 347 to 3 sf, not 350)
c) 350.0, which has been rounded to 1 decimal place.
2) A calculator is 16cm long, to the nearest cm. What are the upper and lower bounds of its length?
3) A cube has side lengths 30cm, to 2 sig figs. What is the maximum possible volume of the box?Post rating:1 
 Follow
 1107
 20082016 14:41
(Original post by KMan_PhysCheM)
I agree with B_9710: they are all correct, but again the two which he mentioned have too many trailing 0s on the end, so it looks like you're expressing it to more significant figures than you are. That's a tiny detail, though, and you shouldn't worry too much about it, but it's good practice to avoid excess 0s after the decimal point and after the stated significant figures.
Here are some bounds questions (remember, bounds are the highest and lowest numbers that would round to the given number at its given accuracy).
1) Find the upper and lower bounds of the following:
a) 350, which has been rounded to 2sf (note: 347 = 350 to 2 sf)
b) 350, which has been rounded to 3sf (note: 347 this time = 347 to 3 sf, not 350)
c) 350.0, which has been rounded to 1 decimal place.
2) A calculator is 16cm long, to the nearest cm. What are the upper and lower bounds of its length?
3) A cube has side lengths 30cm, to 2 sig figs. What is the maximum possible volume of the box?
Posted from TSR Mobile 
 Follow
 1108
 20082016 14:46

 Follow
 1109
 20082016 14:51
Questions C
Posted from TSR Mobile 
 Follow
 1110
 20082016 14:55
You can also look back at your answer and think: do my bounds, when rounded to 2 sig figs, give 350? 34.5 and 35.5 would be the bounds for 35, but what are the bounds for 350? 
 Follow
 1111
 20082016 14:57
(Original post by KMan_PhysCheM)
You don't want to eliminate the 0 from 350. Imagine spending £35 compared to £350 > there's a big difference. On the other hand, spending £35 or £35.00 is the same amount of money, but one has been expressed with greater precision.
You can also look back at your answer and think: do my bounds, when rounded to 2 sig figs, give 350? 34.5 and 35.5 would be the bounds for 35, but what are the bounds for 350?
And 340.5 for LB
Posted from TSR Mobile 
 Follow
 1112
 20082016 14:59

 Follow
 1113
 20082016 15:04
Spoiler:ShowThe first 2 sig figs in 340.5 are 3 and 4. To the left of the 4 is a 0, so the 4 doesn't round up. So that means that 340.5 to 2 sig figs is 340. Hence 340.5 cannot be one of the bounds.
Also, 350.5 does round to 350, but is it really the upper bound? Doesn't 354 also round to 350, to 2 sf? 
 Follow
 1114
 20082016 15:07
(Original post by KMan_PhysCheM)
Are you sure that 340.5 rounds to 2 sig figs to give 350?
Spoiler:ShowThe first 2 sig figs in 340.5 are 3 and 4. To the left of the 4 is a 0, so the 4 doesn't round up. So that means that 340.5 to 2 sig figs is 340. Hence 340.5 cannot be one of the bounds.
Also, 350.5 does round to 350, but is it really the upper bound? Doesn't 354 also round to 350, to 2 sf?
Any videos or anything!
I don't get this whole 3sf and 2sf and 1 dp.
Posted from TSR Mobile 
 Follow
 1115
 20082016 15:13
(Original post by z_o_e)
I don't understand this!!!
Any videos or anything!
I don't get this whole 3sf and 2sf and 1 dp.
Posted from TSR Mobile
https://www.youtube.com/watch?v=8Rkz4UuFS_k 
 Follow
 1116
 20082016 15:16
What do you need help with? Any particular question?

 Follow
 1117
 20082016 15:18
(Original post by RDKGames)
What do you need help with? Any particular question?
Posted from TSR Mobile 
 Follow
 1118
 20082016 15:34
Here's my explanation:
Rounding to Significant Figures: read a number from left to right and round to however figures you need to. The first digit is the first figure, the second digit is the second figure, and so on. If the first figure you encounter is 0, then this is NOT a significant figure, same goes for any 0's that follow it up until you encounter a digit which is not a 0. This would mark the first significant figure, and any number after that one, INCLUDING any 0s, will be considered to be significant. The number 3646 rounded to one s.f. would be 4000. You need to look at the first significant figure, then see whether the digit after that one would make it round 'down' or round up. For two s.f. it would be 3600. And for three s.f. it would be 3650. Of course when it comes to something like 0.00145, rounding to one s.f. would be 0.001, because the first three figures are 0s hence they are not considered to be significant. That number to two s.f. would be 0.0015.
Rounding to Decimal Places: you would ignore all the numbers from left to right until you hit the decimal point. From that point you need to count the decimal places that you are required for the question. For example; 32.5481 to one d.p. would be 32.50000. To two d.p. it would be 32.5500 (because the 8 after the 4 makes it round up), and to three d.p. it would simply be 32.5480. Of course, you can ignore any 0s at the very end of the decimal.
Hope this makes sense.
When it comes to 350 and its UB and LB, you are told that it is rounded to 2 s.f. which means you look for a number where the limits are gong to make it round to 350. This would be 345 (LB) and 355 (UB). You can check this because 345 rounded to 2 s.f. would be 350.
Try to apply this to other questions.Last edited by RDKGames; 20082016 at 15:37.Post rating:1 
 Follow
 1119
 20082016 16:00
(Original post by RDKGames)
Not quite. You need to understand the difference between significant figures and decimal places. The video he posted gives a good explanation on them.
Here's my explanation:
Rounding to Significant Figures: read a number from left to right and round to however figures you need to. The first digit is the first figure, the second digit is the second figure, and so on. If the first figure you encounter is 0, then this is NOT a significant figure, same goes for any 0's that follow it up until you encounter a digit which is not a 0. This would mark the first significant figure, and any number after that one, INCLUDING any 0s, will be considered to be significant. The number 3646 rounded to one s.f. would be 4000. You need to look at the first significant figure, then see whether the digit after that one would make it round 'down' or round up. For two s.f. it would be 3600. And for three s.f. it would be 3650. Of course when it comes to something like 0.00145, rounding to one s.f. would be 0.001, because the first three figures are 0s hence they are not considered to be significant. That number to two s.f. would be 0.0015.
Rounding to Decimal Places: you would ignore all the numbers from left to right until you hit the decimal point. From that point you need to count the decimal places that you are required for the question. For example; 32.5481 to one d.p. would be 32.50000. To two d.p. it would be 32.5500 (because the 8 after the 4 makes it round up), and to three d.p. it would simply be 32.5480. Of course, you can ignore any 0s at the very end of the decimal.
Hope this makes sense.
When it comes to 350 and its UB and LB, you are told that it is rounded to 2 s.f. which means you look for a number where the limits are gong to make it round to 350. This would be 345 (LB) and 355 (UB). You can check this because 345 rounded to 2 s.f. would be 350.
Try to apply this to other questions.
Posted from TSR Mobile 
 Follow
 1120
 20082016 16:01
(Original post by RDKGames)
Not quite. You need to understand the difference between significant figures and decimal places. The video he posted gives a good explanation on them.
Here's my explanation:
Rounding to Significant Figures: read a number from left to right and round to however figures you need to. The first digit is the first figure, the second digit is the second figure, and so on. If the first figure you encounter is 0, then this is NOT a significant figure, same goes for any 0's that follow it up until you encounter a digit which is not a 0. This would mark the first significant figure, and any number after that one, INCLUDING any 0s, will be considered to be significant. The number 3646 rounded to one s.f. would be 4000. You need to look at the first significant figure, then see whether the digit after that one would make it round 'down' or round up. For two s.f. it would be 3600. And for three s.f. it would be 3650. Of course when it comes to something like 0.00145, rounding to one s.f. would be 0.001, because the first three figures are 0s hence they are not considered to be significant. That number to two s.f. would be 0.0015.
Rounding to Decimal Places: you would ignore all the numbers from left to right until you hit the decimal point. From that point you need to count the decimal places that you are required for the question. For example; 32.5481 to one d.p. would be 32.50000. To two d.p. it would be 32.5500 (because the 8 after the 4 makes it round up), and to three d.p. it would simply be 32.5480. Of course, you can ignore any 0s at the very end of the decimal.
Hope this makes sense.
When it comes to 350 and its UB and LB, you are told that it is rounded to 2 s.f. which means you look for a number where the limits are gong to make it round to 350. This would be 345 (LB) and 355 (UB). You can check this because 345 rounded to 2 s.f. would be 350.
Try to apply this to other questions.
,
Posted from TSR Mobile
Write a reply…
Reply
Submit reply
Register
Thanks for posting! You just need to create an account in order to submit the post Already a member? Sign in
Oops, something wasn't right
please check the following:
Sign in
Not got an account? Sign up now
Updated: December 3, 2016
Share this discussion:
Tweet
Related discussions:
 The Current Year 11 Thread Mark I (20162017)
 The Current Year 11 Thread Mark I (20162017)
 GCSE GYG  1st Year
 GCSE GYG  1st Year
 What happens if I fail my Foundation Maths GCSE?
 PurpleFireQueen's guide to not failing at ALevels!
 CutieTootsie's road to A*A*A*
 Niamh's Path to Perfection!
 The Journey of an Aspiring Vet
 CutieTootsie's road to A*A*A*
TSR Support Team
We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.