Two cylindrical elements, X X\,X and YYY, are made of the same uniform alloy, have equal length LLL, and are connected in series as part of a high-temperature probe.
The diameter of element Y Y\,Y is 1.5 times that of element XXX. The resistance of element Y Y\,Y is RRR.
What is the total electrical resistance of the series combination?
139R\frac{13}{9}R913R
52R\frac{5}{2}R25R
134R\frac{13}{4}R413R
53R\frac{5}{3}R35R