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प्रश्न
In a certain town, a viral disease caused severe health hazards upon its people disturbing their normal life. It was found that on each day, the virus which caused the disease spread in Geometric Progression. The amount of infectious virus particle gets doubled each day, being 5 particles on the first day. Find the day when the infectious virus particles just grow over 1,50,000 units?
उत्तर
a = 5, r = 2,
tn >150000,
To find ‘n’
tn = arn–1 = 150000
(i.e) 5(2)n–1 = 150000
⇒ 2n–1 = `150000/5` = 30000
215 = 32768 and 214 = 16384
We are given 2n–1 > 30000
⇒ 215 = 32768 > 30000
⇒ n – 1 = 14
⇒ n = 15
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