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1. Find the '''half life''' of this [[sample]] of [[radioactive]] [[isotope]].:The '''half life''' of of this [[sample]] of [[radioactive]] [[isotope]] can be found by halving the initial count rate.
:1000/2 = 500Bq
:The [[isotope]] took 20 seconds to half in [[Count Rate|count rate]] so the ::'''half Half life''' is = 20 [[seconds]].
The 2. Predict the [[Count Rate|count rate]] at 90 seconds can be predicted. :Since the '''half life''' is 20 seconds the [[Count Rate|count rate]] 20 seconds earlier can be halved. :At 70 seconds the [[Count Rate|count rate]] was 88Bq. Therefore at 90 seconds the [[Count Rate|count rate]] would be:
:88/2 = 44Bq
The 3. Predict what the [[Count Rate|count rate]] at was 10 seconds before the [[sample ]] was first tested can also be predicted. :Since the '''half life''' is 20 seconds the [[Count Rate|count rate]] 20 seconds later can be doubled. :At 10 seconds the [[Count Rate|count rate]] was 707Bq. Therefore at -10 seconds the [[Count Rate|count rate]] would have been: 707x2= 1414Bq
:707x2= 1414Bq
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