Answer:
The total energy saving achieved will be 0.8 KWH
Explanation:
It is provided that there are 50 long light bulbs rated at 100 W, thus the total power consumed by 50 bulbs equals 100×50 = 5000 W = 5 KW
Additionally, 30 bulbs are rated at 60 W
Consequently, the total power consumption of 30 bulbs is 30×60 = 1800 W = 1.8 KW
The cumulative power of all 80 bulbs is 1.8 + 5 = 6.8 KW
Considering the operation time of 3 hours
We know that energy 
Now, the power consumption per CFL bulb equals 25 W
Thus for 80 bulbs, power equals 80×25 = 2000 W = 2 KW
So the energy for 80 bulbs amounts to 2×3 = 6 KWH
Hence, the overall energy saving is 6.8 - 6 = 0.8 KWH
12 degrees = (π / 180) x 12 radians =.2093 radians; the position of the third bright fringe is determined as 3λ D/d, where λ represents the light wavelength, D is the distance to the screen, and d is the slit separation. Thus, the equation results in 3λ D/d = 30 x 10⁻², and from the angular separation, we deduce 3λ/d =.2093. Substituting the two equations, we find.2093 D = 30 x 10⁻², leading to D = 30 x 10⁻² /.2093 = 1.43 m.