Auteur Message
JoeClark

Hors ligne

Inscrit le: 21 Sep 2017
Messages: 119
Profession: Manager
Moyenne de points: 0

 Posté le: Jeu 30 Nov - 11:08 (2017)    Sujet du message: when calculating a difference using two rounded down values. I have a maths question from an old text book where I disagree with the answer given.You have 2 pins. One is measured as 12mm and the other is 14mm.The values measured are rounded down to the nearest mm.That means the true length of each pin "l1" and "l2" by my calculation would be:-12 <= l1 < 1314 <= l2 < 15That means the actual error for each pin is:--1 < E1 <= 0-1 < E2 <= 0That means that the maximum absloute error for each pin is just under 1mm.My problem is what is the maximum absolute error when calculating the difference between the two pins?Using the given values: 14mm - 12mm = 2mm.The largest l1 can be is just under 13mm and the lowest l2 can be is 14mm giving a difference of 14mm - 13mm = 1mm.The lowest l1 can be is 12mm and the largest l2 can be is 15mm giving a difference of 15mm - 12mm = 3mm.Therefore I calculate the true difference as:-1 < (l2-l1) < 3That means the actual error when calculating the difference is:--1 < E3 < 1And so the maximum absolute error in calculating the difference is just under 1mm.I believe the book says that maximum absolute error in calculating the difference should be just under 2mm (combining the two errors of each measurement) but I can't find a way to combine the errors in this case.Anyway I needed to check if I was right or if there was something I'm missing before moving on. Thank you in advance for any replies.I didn't find the right solution from the Internet.Referenceshttps://www.freemathhelp.com/forum/threads/108838-Maximum-absolute-error-when-calculating-a-difference-using-two-rounded-down-values
Jeu 30 Nov - 11:08 (2017)
Auteur Message
Publicité

Posté le: Jeu 30 Nov - 11:08 (2017)    Sujet du message: Publicité
 Publicité Supprimer les publicités ?
Jeu 30 Nov - 11:08 (2017)
 Page 1 sur 1 Toutes les heures sont au format GMT + 3 Heures

Montrer les messages depuis:

 Sauter vers: Sélectionner un forum----------------A Lire Avant Tout   Charte du Forum   Mode MathsKomoriMaths   Algèbre   Analyse   Arithmétique et Nombres   Géométrie   Enigmes   Hors Maths

Index | créer un forum | Forum gratuit d’entraide | Annuaire des forums gratuits | Signaler une violation | Conditions générales d'utilisation