Mass = Volume/Density. The answer is 9.8kg
Answer: 3P/2
Explanation: Let the resistance of the bulbs be R.
now lets consider a Voltage V is supplied to the parallel circuit such that

V=IR
both single bulb( bulb 3) and the two bulbs ( bulb 1 and bulb 2) are provided the same Voltage
( as the voltage remains same in parallel circuit)
we can calculate the Current across both circuits
At Bulb 3
Current 1=V/R
Power1=Voltage * Current1
Power1=V*V/R
Power1=P
At Bulb 1 and Bulb 2
Total Resistance= R+R=2R

Power2=Voltage * Current2


A "folk" remedy is something you choose to eat, take, or do,
in order to correct some health issue, because your friend,
your grandmother, your religion, your shaman, your astrologer,
or your medicine man says that it's the right thing to do.
It may or may not be effective, and it may or may not even be
safe. What distinguishes it from mainstream medicine is that
its practices are based on hearsay, and have not been subjected
to scientific methods of investigation and evaluation.
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According to Newton's 3rd law of motion, every action has an equal and opposite reaction.
So Wall must apply a force of 50 Newton but in opposite direction.
Hope you got it :-D