SOLUTION: in an attempt to discreadit the persident, a member of the opposite political party wishes to start a scandakous rumor about him. he plans to tell people this rumor one week before

Question 1963: in an attempt to discreadit the persident, a member of the opposite political party wishes to start a scandakous rumor about him. he plans to tell people this rumor one week before the election day and wants the entire population of the united staes (that's 250,000,000 people!) to know the rumor. he needs to figure out how many people he should tell (and they each will tell the same number of people) so that everyone will have heard the rumor by the seventh day.
Answer by longjonsilver(2297) (Show Source): You can put this solution on YOUR website!
this is a geometric progression (GP), where you start with a value and then multiply a fixed amount to each subsequent value, so for example...
1 + 2 + 4 + 8 + 16 + 32 + 64 = whatever... this is starting with 1 and multiplying 2 to each value.
the issue with your question, which is always debateable...do we start with 1 person (ie the man in question) or do we start with the number of people he just told...call it x? Also, where do we start from and where do we end? Beginning of DAY1 with himself?
Beginning of DAY1 with x people?
End at START of DAY7 with people telling their next lot?
basically it will either be
=250,000,000
or
=250,000,000
This is nothing to do with you, just the question being ambiguous.
As to how to solve this, well that is another question :-).
For a GP, starting at a with constant ratio r over n terms, the sum of these is given by the formula
here, a will be 1 or x
r will be x
n will be 7
and the sum itself will be 250,000,000. You will need to find x.
Jon
RELATED QUESTIONS
Burton High School has 1,500 students. During first period, a rumor is started when Susan (answered by stanbon)

If all who hear a rumor repeat it to two people a day, and if 20 people start the rumor,... (answered by jsmallt9)

If all who hear a rumor repeat it to two people a day, and if 10 people start the rumor, (answered by jim_thompson5910)

If all who hear a rumor repeat it to 2 people a day, and if 10 people start the rumor,... (answered by nerdybill)

The numbe of people who hear a rumor increases exponentially. If 20 people start a rumor (answered by stanbon)

A rumor is spread randomly among a group of 10 people by successively having one person... (answered by CPhill)

4000 adults were asked if they voted in the last election and if they were members of the (answered by CPhill)

AT 8AM 7 PEOPLE HAVE HEARD A RUMOR. AT 11AM 75 PEOPLE HAVE HEARD THE SAME RUMOR. LET F(T) (answered by CharlesG2,stanbon)

Tara is 7th grader student at Swat Middle School in Bugsville, USA. She decides to start... (answered by stanbon)