Question

Researchers at the Centers for Disease Control and Prevention have been studying the decay pattern of a new virus with a decay rate of 19% per hour. They start with 300 viruses that they want to check on in the next 7 hours. How many viruses will they find in 7 hours? Round your answer to the nearest whole number

Answer 1

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,

                                                  $y = A(1-r)^{t}$............................(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,

                                            $y = 300(1-0.19)^{7}$

                                               $= 300(0.81)^{7}$

                                               $= 300(0.228767)$

                                               $= 68.63$

               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.