What is the product of seven and eight decreased by “x” if x =15?
2 answers:
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Let, the number be "a"
Now, according to the question,
So, the number is 72
Now, according to the question,
So, the number is 72
The Researcher will find 69 viruses, because 231 viruses are decayed in 7 hours, if a virus with a decay rate of 19% per hour and they start with 300 viruses.
Step-by-step explanation:
The given is,
A new virus with a decay rate of 19% per hour
They start with 300 viruses
Step:1
Formula to calculate the viruses at decay rate,
............................(1)
Where, y - No of viruses after given time
A - Viruses at initial stage
r - Decay rate
t - No. of hours
From the given,
A = 300
r = 19% per hour
t = 7 hours
Equation (1) becomes,
Viruses of 7 hours ≅ 69 viruses
( or )
Step:1
For 1st hour,
= (No.of viruses in hour) - (No,of viruses in last hour × Decay rate )
= (300)-(300 × 0.19)
= 300 - 57
= 243
For 2nd hour,
= (243)-(243 × 0.19)
= 243 - 46.17
= 196.83
For 3rd hour,
= (196.83)-(196.83 × 0.19)
= 196.83 - 37.39
= 159.4323
For 4th hour,
= (159.4323)-(159.4323 × 0.19)
= 159.4323 - 30.2921
= 129.1402
For 5th hour,
= (129.1402)-(129.1402 × 0.19)
= 129.1402 - 24.5366
= 104.6035
For 6th hour,
= ( 104.6035)-( 104.6035 × 0.19)
= 104.6035 - 19.8747
= 84.7288
For 7th hour,
= (84.7288)-(84.7288 × 0.19)
= 84.7288 - 16.0984
= 68.63 viruses
Result:
The Researcher will find 69 viruses, because 231 viruses are decayed in 7 hours, if a virus with a decay rate of 19% per hour and they start with 300 viruses.