Answer:
1. The current will drop to half of its original value.
Explanation:
The problem can be solved by using Ohm's law:

where
V is the voltage across the circuit
R is the resistance of the circuit
I is the current
We can rewrite it as

In this problem, we have:
- the resistance of the circuit remains the same: R' = R
- the voltage is decreased to half of its original value: 
So, the new current will be

so, the current will drop to half of its original value.
If you give us the situation described then I'll be able to help.
Answer:
55%
Explanation:
take efficiency=power output/power input multiply by 100%
Answer:
10 years
Explanation:
As you can understand from the question it is given that the planet is already filled to half of its capacity. Also the population doubles in 10 years. To fill up the planet completely the population needs to double only once. To do that only 10 years are required.
As it is mentioned there are no other factors affecting the growth rate, in 10years the planet will be filled to its carrying capacity.