Answer:
It has been delivered that out of three buckets, under two buckets, there is a 1-oz gold bar and under the outstanding one there is 5-oz gold bar.
After a choice has been finished by the contender, host has elevated one bucket and under it 1-oz gold bar was originate.
So, after this, two buckets had been left.
Out of this two buckets, one covers 5-oz gold bar and second cover 1-oz gold bar.
Selecting out of these two buckets makes 50-50 chances of either winning 5-oz gold bar or 1-oz gold bar.
Compute prospect of participant winning 1-oz gold bar -
Number of buckets under which 1-oz gold bar is placed = 1
Total number of buckets = 2
P (winning 1-oz gold bar) = Number of buckets under which 1-oz gold bar is placed/Total number of buckets
P (winning 1-oz gold bar) = 1/2
Hence, the correct answer is option (3).