Gregmat Quant Concept data analysis problem

In today’s quant concept class in the last data analysis problem the equation was kept as 2^40-1/100. However, when I checked the formula for sum of geometric progression it seemed to me the equation would be 2(2^40-1)/(2-1). Could anyone please clarify which one would be correct? For convenience I attached the problem and also the formula.


In the first screenshot, the first term of the progression is 2…but in today’s question it starts with 1.
So a = 1.

Thanks but it’s not clear then why 2^40-1/100

Is it actually 1(2^40-1)/2-1

yes you’re correct. Where did 100 come from?

1 Like

Not sure. Was in the screenshot.