Question 1198321
.
A teacher is manually checking her student's outputs. 
She opens the submission bins and encodes scores in her class record. 
She checks twice as many outputs in the next hour as compared to the previous hours she is working. 
How many outputs has the teacher checked if she was able to grade five outputs 
in her first hour of working and she was able to work for four hours?
~~~~~~~~~~~~~~~


<pre>
 5 outputs are checked in the 1st hour.

10 outputs are checked in the 2nd hour.

20 outputs are checked in the 3rd hour.

40 outputs are checked in the 4th hour.


They want you calculate this sum  5 + 10 + 20 + 40.
</pre>

Solved (at least, explained for you).