cjiang16 wrote:Using estimation, the answer is B.

1. 2^10
2. 2^11
3. 2^18
4. 2^54
5. 2^56

resilient wrote:2+2+2^2+2^3+2^4+2^5+2^6+2^7+2^8+2^9+2^10=

1. 2^10
2. 2^11
3. 2^18
4. 2^54
5. 2^56


The answer is 2^11
Remove the first term (2) and take a look at the remaining portions. They are in the Geometric Progression.
So the formula to find the sum of n terms of a geometric progression is S=b1*(1-r^n/1-r), where b1 is the first term, r is the ratio between the two variables, in this case r=2 (ie, third term divided by second term)
By using this formula, I got S=2046.
Now add the term '2' we removed to this figure(s=2046) which gives you 2048.
We know 2^10 is 1024 so 2^10*2=2048.
So the answer is 2^10*2^1 ,which is equal to 2^11, option B.