Physics help

[farahdar]

Q31 Nov 10 MCQs :When three identical resistors are connected in series, their combined resistance is 6 Ω. What is their combined resistance when they are connected in parallel?
From my understanding it should be C but the marking scheme says B..Whats right?

 

[Sarosh Manzar]

The formula for resistance in parallel is 1/R = 1/R1 + 1/R2 + 1/R3 , since one resistor is 2Ω, that would give 1/R = 3/2 , therefore R will be 2/3 , which is B

 

[farahdar]

Oh, my bad..Didn't keep in mind the 1/R thing so stuck to 3/2..Thanks