Can someone check my answer please? The one I have clicked is my answer choice.

Question

liv1234 · Answer

@welshfella

liv1234 · Answer

@pooja195

welshfella · Answer

sum of 15 terms = 2 * 1 - 0.5^15
                                    ---------
                                        1 - 0.5

luckyness · Answer

I believe its correct, Although I would check with Welsh :)

liv1234 · Answer

I got 1.5

liv1234 · Answer

@welshfella

welshfella · Answer

No its not 1.5  
use the formula 
work out
1 - 0.5^15
divide this by 0.5 

then multiply by the first term 2

use your calculator 
it might not give you the exact answer - but very close

welshfella · Answer

the formula is  S   = a1 ( 1 - r^n)
                                     -------
                                      1 - r
in your case a1 = 2 , n = 15 and r = 1/2 (or 0.5)

liv1234 · Answer

Okay, but I keep getting 1.5

welshfella · Answer

what tdo you get for 1 - 0.5^n ?

welshfella · Answer

- you work out the parentheses first

welshfella · Answer

i used my calculator and it give me 0,.999694824
but we can call that 1

so multiply 1 by 2 
then divide by 0.5

welshfella · Answer

Sum  =   2 * 1
              -----
                 0.5

welshfella · Answer

2 / 0.5 =  ?

welshfella · Answer

just work that out on your calculator id you are not ccconfident to do it manually.

liv1234 · Answer

I got 4

liv1234 · Answer

Sorry for the late response, OpenStudy was being slow

welshfella · Answer

thats right 

thats the naswer

liv1234 · Answer

Thank you!

welshfella · Answer

naswer  - lol!!

welshfella · Answer

yw

welshfella · Answer

its worth trying to remember that formula for sum of n terms of a Geometric series.