Answers

2016-07-16T14:37:39+08:00
Given : a_{1}=40, r= \frac{1}{2}

To solve,
 
            S_{n}=a_{1} \frac{1-r^n}{1-r}
            S_{n}=40 \frac{1- \frac{1}{2}^6 }{1- \frac{1}{2} }
            S_{n}=40 \frac{1- \frac{1}{64} }{- \frac{1}{2} }
            S_{n}=40 \frac{ \frac{63}{64} }{- \frac{1}{2} }
            S_{n}=40[ \frac{63}{64}(-2)]
            S_{n}=40 \frac{-126}{64}
            S_{n}= \frac{5040}{64}
            S_{n}=78.75
0
a.315/4 b.315/2 c.315/8 d.315 is it the letter b?
nope. it is A.
how did you come up with a?I'm curios
we have the same solutions right? so the answer is 78.75 .. you just have to divide 315 by 4 .
the answer 78.75... but you choose letter A.. how? pls explain,,