Sequence A is a geometric sequence. Sequence B is an arithmetic sequence. Each sequence stops as soon as one of its terms is greater than 300. What is the least positive difference between a number selected from sequence A and a number selected from sequence B?

Sequence A: 2, 4, 8, 16, 32, ...

Sequence B: 20, 40, 60, 80, 100, ...

Lightning
Sep 3, 2018

#1**+1 **

First, we have to see what the least difference between any could be. We find the least distance to be possible, for example, when there is 64 and 60, because the difference is there 4 and otherwise, it would be a higher number.

I will list out the numbers for anyone who wants to try and prove me wrong (not that I'm saying you're a bad community, this is a great one) :

Sequence A: 2, 4, 8, 16, 32, 64, 128, 256, 512

Sequence B: 20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320

The answer is 4

mathmagical
Sep 24, 2018