In the series circuit below the power source is a 9-volt battery and three resistors are r1 = 7 ohm, r2 = 9 ohm and r3 = 2 ohm. what is the total resistance in the series circuit?
r1 7 ohm + r2 9 ohm + r3 2 ohm = 18
is this correct?

Aprisoner is forced to go into one of three rooms, but he can choose which room. the first room is ablaze with fire. the second one is rigged with explosives that will go off as soon as he enters. the third contains a pair of lions who haven't eaten in years. which room should he choose to survive?