A technician has only two resistance coils. By using them singly, or in series or in parallel, he is able to obtain the resistance 1.5, 2, 6 and 8 ohms. The resistance of two coils are

Let the two resistance be R₁ and R₂ 

Maximum resistance is obtained when both are connected in series = 8 = R₁ +R₂ 

Minimum resistance = 1.5 

 $1.5 = \frac{{\mathrm{R}}_1{\mathrm{R}}_2}{{\mathrm{R}}_1+{\mathrm{R}}_2}=\frac{{\mathrm{R}}_1{\mathrm{R}}_2}{8}$

${\mathrm{R}}_1.{\mathrm{R}}_2= 12$

R₁-R₂ = 4 

R₁ = 6 ohms  and R₂ = 2 ohms