Texas Instruments solar TI-36X User Manual
Page 21
19
Ti36eng1.doc TI-36X II Manual Linda Bower Revised:
01/10/03 10:47 AM Printed: 01/10/03 10:47 AM Page 19 of
48
³
Problem
A radioactive substance decays exponentially. If y
o
grams of certain radioactive substance are initially
present, the number of grams y(t) after t days is given
by the formula:
y(t)=y
o
e
-0.00015t
After 340 days, how much of a 5-gram sample of this
radioactive substance remains? After 475 days? Store
the constant part of the exponent to memory so you
need enter it only once. Round results to two decimal
places.
J 0 I 0 0 0 1 5 S V
L0.00015
ЮA
Я
L0.00015
,-/
5
< % d " " " V
R < 3 4 0 O V
5
èe^(Aи340)
Я
4.751393353
,-/
% t 2
5
è e^(Aи340)
Я
4.75
.1:
,-/
5
< % d " " " V
R < 4 7 5 O V
5
èe^(Aи475)
Я
4.66
.1:
,-/
About 4.75 grams of this radioactive substance remain
after 340 days, and 4.66 grams remain after 475 days.