You are both right, however, you missed my comment about the logical assumption. I assumed a hole with zero diameter thus making the ring height and the sphere diameter the same. Then I used the arithmetic equsion domokato listed.
Ya, the width of the drill was not stated so I just assumed it was negligible.
B. Since both sequences start with HT, we can look at just the last letter, which is either H or T, and the chance of getting H or T are equal. So assuming a sequence ending in HT has been tossed, either H or T will come up next with equal probability, so both chances are equal.
Here’s a fun one. It’s been around a while, so please don’t give it away if you already know the answer.
Three people check into a hotel. They pay $30 to the manager and go to their room. The manager suddenly remembers that the room rate is $25 and gives $5 to the bellboy to return to the people. On the way to the room the bellboy reasons that $5 would be difficult to share among three people so he pockets $2 and gives $1 to each person. Now each person paid $10 and got back $1. So they paid $9 each, totalling $27. The bellboy has $2, totalling $29. Where is the missing $1?
It’s a logical error. The author pulled the ‘ol switch-a-roo. Good one! ( Switching an addition for a subtraction! Clever. If we begin with the original total of $30, and consider that each of three roomies recieved $1, then we subtract each dollar from the $30 to arrive at $27, their final price. But the price they should have had was partly in the bell boy’s pocket, so subtract his $2 to bring the price down to the manager’s price of $25. The puzzle makes one think that the bell boy’s $2 should be added to the $27, which is the reverse operation that is needed. )
At first I thought that it was an off-by-one error, but no. It was clever. I’ve heard sales pitches as sneaky as that. I wish I had sent this before DM figured it out, I’m just too slow!
Effectively C is correct because when throwing to get the sequence HTT and getting it wrong on the last throw (HTH) you already have the first toss in the sequence “in your pocket” whereas failing on HTH you still have to start the desired sequence Smile