Question

are connected in series such that total resistance is 48 ohm if the resistance of 3 resistance is 5 ohm 10 ohm and 12 ohm respectively find the resistance of the fourth resistor

Answer 1

Total resistance =sum of the individual resistance when connected in series.
let the resistance of 4th resistor=x
then 5+10+12+x=48
x=48-27=21
hence the resistance of 4th resistor is 21 ohm

Answer 2

For Resistance in series,
R=R1+R2+R3+R4
or,48=5+10+12+R4
so,
R4=21 ohm