The population of a type of local dragonfly can be found using an infinite geometric series where a1 = 65 and the common ratio is 1/6. Find the sum of this infinite series that will be the upper limit of this population.

78

28

11

32

Question

The population of a type of local dragonfly can be found using an infinite geometric series where a1 = 65 and the common ratio is 1/6. Find the sum of this infinite series that will be the upper limit of this population.


78

 28

 11

 32

anonymous · Answer

@hartnn

campbell_st · Answer

the formula for infinite sum is 

$$S_{\infty} = \frac{a_{1}}{1 - r}$$

just substitute you're values of a1 and r.... to get the solution

anonymous · Answer

yes if you use the formula you get 65/1-(1/6) which is 65/(5/6) or (65*6)/5 which is 390/5=78

anonymous · Answer

Thank you @maida.beganovic

anonymous · Answer

Find the sum of a finite geometric sequence from n = 1 to n = 6, using the expression −2(5)^n − 1.

1,223

 −1,023

 −7,812

 7,812

anonymous · Answer

@maida.beganovic

anonymous · Answer

Do I plug in all the numbers that are from 1-6 and add the answers together? @maida.beganovic

anonymous · Answer

I got -7812! is that the correct answer? @maida.beganovic

anonymous · Answer

yes it's correct but i think you should use the formula because you can only solve it this way for smaller numbers because there are only 6 members of this sequence that you had to add up :)

anonymous · Answer

Find the sum of the summation of 2 i minus 12, from i equals 7 to 16.

 22

 110

 220

 440

anonymous · Answer

@ganeshie8

anonymous · Answer

What did you get for the last one??