SOLUTION: In a speed typing test, each girl found that the girl sit on the left type twice as much as she type. The teacher note that each girl type a whole numbe rof lines and all the girls

Question 555561: In a speed typing test, each girl found that the girl sit on the left type twice as much as she type. The teacher note that each girl type a whole numbe rof lines and all the girls typed 635 lines in total.
How many girl take the test?
Answer by KMST(5328) (Show Source): You can put this solution on YOUR website!
Let the number of words typed by the girl on the right be .
The girl to her left typed words.
The next girl typed words, and so on.
The number of words typed by each girl, from right to left, forms a geometric sequence with common ratio 2.
The sum of the words typed by n girls is

Since both factors must be integer,
, and
5+1=6 is not a power of 2,
it must be and

So and n=7.
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