watts = work per second.
work is mgh = 3x10x50=1500
watts out = 1500
Watts used = 2000
eff=1500/2000=75%
Answer:
Ae/A* = 1.115
Explanation:
Let the reservoir pressure be 
Let the exit pressure be 
Ratio of reservoir pressure and exit pressure

= 3.182
For the above value of pressure ratio
Obtain the area ratio from the isentropic flow table
Ae/A* = 1.115
The value of pressure ratio is Ae/A* = 1.115
<span>The correct answer is blue. If you look at a luminosity star chart, called the Hertzsprung Russell Diagram, you will see the measurement of luminosity on the left side, and you will see a curve of stars with different colors (which correlate to the colors of the stars). Look for 30 on the luminosity measurement (look between 1 and 100). Then, move horizontally across the diagram until you hit the stars, whose color will be blue. Thus, blue is the answer.</span>