Question 1066134
Imagine that someone used invisible ink to label each box with a number,
and knows that boxes number 1 through 17 have decoder rings,
while boxes number 18 through 61 have other gifts.
There are {{{61*60/2=1830}}} possible sets of two boxes that you could select,
but there are only {{{17*16/2=136}}} possible sets of two boxes with decoder rings.
The fraction of possible pairs of boxes where both boxes have the secret decoder ring is
{{{136/183068/915=about0.074}}}
The probability that both of the boxes you select had decoder rings is
about {{{highlight(0.074="7.4 %")}}} (rounded).