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According to an ancient belief, when a friend visits a sick person, \(\frac{1}{60}\) of his or her illness is taken away. How many friends need to visit to take away at least 99% of a person's illness?

 

A. 375

 

B. 180

 

C. 275

 

D. 125

 

E. 55

 

Please explain, I am confused on this problem

 Feb 16, 2019
edited by CalculatorUser  Feb 16, 2019
 #1
avatar+98182 
+3

If 1/60 is taken away after a visit .....then 59/60  must remain after a visit

 

So.....we want to find out how many visits are required to have   1%  =  1/100 left

 

So.....we want to solve this

 

(59/60)^N  =   1/100         where N is the number of required friends

 

Take the log of both sides

 

log (59/60)^N  =  log (1/100)      and by a log property, we can write

 

N * log (59/60) = log (1/100)     divide both sides by log(59/60)

 

N =    log(1/100) / log (59/60)   ≈  274.001 friends

 

We'll call  275  good      .....!!!

 

 

cool cool cool

 Feb 16, 2019
edited by CPhill  Feb 16, 2019
 #2
avatar+244 
+1

Thanks CPhill! I understand now!

 Feb 16, 2019
 #3
avatar+98182 
+2

OK, CU.....glad to  help....

 

cool cool cool

CPhill  Feb 16, 2019

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