Answer:
169.50
Step-by-step explanation:
<u>Understanding:</u>
The sum of a geometric series is,
, with a being the start point and r is the common ratio. We can also use the following formula to make life easier
, a is your start point, r is the common ratio, and n is the number of terms, which in our case is S7.
<u>Solution:</u>
Our start point is 1,
,
The common ratio is 5,
,
And finally, the number of terms is 7,
.

The answer is [A] 19531.
We know that
Applying the Pythagoras Theorem
c=²=a²+b²
where c is the diagonal of the wall
a=12 ft
b=6 ft
c²=12²+6²-----> c²=144+36-----< c²=180-----> c=√180------> c=6√5 ft
the answer is
<span>the exact length of the brace is 6</span>√5 ft