Texas Instruments TI-36X manual 5 %dV, 1 ,- 4, J0 I0 0 0 1 5 SV, R3 4 0 OV, R4 7 5 OV, L0.00015 ÞA

³ Problem

A radioactive substance decays exponentially. If yo grams of certain radioactive substance are initially present, the number of grams y(t) after t days is given by the formula:

y(t)=yoe-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.

J0 I0 0 0 1 5 SV	L0.00015ÞA	ß
	L0.00015,-/
5 <%d"""V	5èe^(Aè340)	ß
R<3 4 0 OV	4.751393353,-/
%t2	5è e^(Aè340)	ß
	.1: ,-4/.75
5 <%d"""V	5èe^(Aè475)	ß
R<4 7 5 OV	.1: ,-4/.66

About 4.75 grams of this radioactive substance remain after 340 days, and 4.66 grams remain after 475 days.

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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