Mess up the brain teaser interview so bad

yesterday was having interview with 2 team members separately, i asked the hr about what type of interview would be ,is it case study or behavioral one, and hr told me just normal conversation about my skills and experiences nothing fancy.

When i met with the first team member, he came up and said we are going to have a small case interview and i was shocked, but i finished it and i think i did ok.

The second member showed up and said we are going to have some brain teasers and I was more shocked but i pretend that i am confidend that i can ace it. however, I was stupidly wrong. I did not do well and actually did quite bad on it , I have to ask her to help. there are 3 questions and i merely can solve 2 out of 3 with her hints. I think i definitely got rejected.

I was interviewed with a consulting firm and brain teaser was not about any type of market sizing or what so ever, its about "if the sphere of the original circle is 2pir, and there is a rope and i added 12 inches on it to circle it ,can you calculate the distances between it." this is quite easy i konw, but at that time i was so underprepared about the brain teaser, my head was a mess and i felt nervous about it.