There is a rectangle with length 10cm and width 6cm, where all measurements are corrected to the nearest cm.
If the actual value of the perimeter is p cm, find the range of values of p.
Ans.:30<=p<34
Why the answer is not 30<=p<=34 ???
Please explain, thz!
Maths (measurement)
2012-11-07 7:06 am
回答 (2)
2012-11-07 7:29 am
✔ 最佳答案
Because the data are to be corrected.If the length >10.4 e.g 10.45<--this will be corrected to 10.5 but not 10
the width >6.4 e.g 6.45<--also will be corrected to 6.5 not 6
So,we can know that ,the length and the width must be <=10.4 and <=6.4 respectively.
The greatest value of p =(10.4+6.4)x2
p =33.6.
Therefore the value of p must<34,it can not be equal to 34.
2012-11-07 7:19 am
The range of length 9.5 <= x < 10.5
The range of width 5.5 <= y < 6.5
As p = 2(x + y)
Min. of p = 2(9.5 + 5.5) = 30
Max. of p < 2(10.5 + 6.5) = 34
So, 30 <= p < 34
The range of width 5.5 <= y < 6.5
As p = 2(x + y)
Min. of p = 2(9.5 + 5.5) = 30
Max. of p < 2(10.5 + 6.5) = 34
So, 30 <= p < 34
收錄日期: 2021-04-23 21:20:46
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20121106000051KK00582