TechnologyNote:To makethis computationwith a graphingcalculatorof the TI-83/84family, do the fol-
lowing:
- FromtheDISTRmenu(Figure27) selectoption2, whichputs the phrase"normalcdf"in the homescreen.
Add lowerbound,upperbound,mean,standarddeviation,separatedby commas,closethe parentheses,
and pressENTER. The resultis shownin Figure28.
Figure 27
Figure 28
- For the probabilitythat a box weighsless than ounces,we use the area underthe curveto the left
of Sincethe valueof is very small(lessthan a billionth),
gettingthe area between and will yield a fairlygoodanswer. Integratingnumerically, we get
whichsays that we wouldexpect of the boxesto weighless than ounces.
- Theoreticallythe probabilityhere will be exactlyzero becausewe will be integratingfrom to which
is zero.However, sinceall scaleshavesomeerror(call it ), practicallywe wouldfind the probabilitythat
the weightfalls between and.