₦airaland Forum

GenBuhari:
may have made error as i did this last calculation mentally.
if first gold ball came from box1 , then Pr of 2nd gold ball would be 1/2
if first gold ball came from box2, then Pr of drawing 2nd gold ball will 1/3

average of the 2 options is 5/12
I believe this must be best solution or answer.

GenBuhari:
OP saying my answer is flawed prompted me to look at my solution.
They ate two ways a second consecutive gold could be picked and the probabilities of both options differ, so I calculated probabilities for both option and took an average of the two probabilities to be the probability of picking the second gold ball.

This gave the answer; 5/12 (42%)

nairaman66:
A quick one!

There are 5 Stables in a row numbered 1 to 5, in which a horse is hiding. Every night the horse jumps to an adjacent stable, and every morning you have one chance to open a stable to find the horse. How do you solve this game of hide and seek?

emae009:
The OP is correct, the answer to the first test is 1/2 or 50%. Let me simplify it:
1) after eliminating box SS by picking a G ball.
2) you're left with 2 boxes: & GS.
here lies the logic:
3) if you picked the G ball from box , then the probability of picking another G ball is 1 since you're picking from the same box again.
4) if you picked the G ball from box GS, then the probability of picking another G ball is 0 since you're picking from the same box again.
so therefore we have two outcomes; it's either you pick a G ball or you don't pick a G ball so the answer becomes 1/2 or 50%


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