Answer:
(3) 4.62 ohms
Step-by-step explanation:
Te equivalent resistance R is gotten from
1/R = 1/R₁ + 1/R₂ + 1/R₃ where R₁ = 10.0 ohm, R₂ = 15.0 ohm and R₃ = 20.0 ohm
1/R = 1/10 + 1/15 + 1/20
1/R = 0.1 + 0.0667 + 0.05
1/R = 0.2167
R = 1/0.2167
R = 4.62 ohms