So, first, we need to convert the lifetime of the Sun left into seconds as the mass lost is given per second. To do this we do the following:
5x10^9 * 365 (number of days in a year) * 24 (24 hours in a day) * 60 (how many minutes there are in an hour) * 60 (how many seconds there are in a minute) .
This gives 1.5768x10^17 seconds. This is how many more seconds that the Sun has remaining in its lifetime.
To calculate how much of the mass will be lost in this amount of time, we just multiply 1.5768x10^17 by 4.3x10^9 (if 4.3x10^9 kg is lost every second and the Sun has 1.5768x10^17 seconds remaining, then we just multiply the two numbers to calculate the total mass lost).
Multiplying these two numbers gives 6.78024x10^26 kg. This is the total mass of the Sun that will be converted to energy in the remainder of the Sun's lifetime.
To calculate the percentage we must do: mass lost / original mass of the sun and multiply the value by 100%.
In other words:
((6.78024x10^26)/(2.0x10^30)) x 100% to get: 0.034% (to 2 decimal places).
I am not quite sure why the responses are getting deleted. Sheyda already responded to this, but I am just repeating it in case someone else doesn't know what the notation * means. It just another way of saying multiply.
So, first, we need to convert the lifetime of the Sun left into seconds as the mass lost is given per second. To do this we do the following:
5x10^9 * 365 (number of days in a year) * 24 (24 hours in a day) * 60 (how many minutes there are in an hour) * 60 (how many seconds there are in a minute) .
This gives 1.5768x10^17 seconds. This is how many more seconds that the Sun has remaining in its lifetime.
To calculate how much of the mass will be lost in this amount of time, we just multiply 1.5768x10^17 by 4.3x10^9 (if 4.3x10^9 kg is lost every second and the Sun has 1.5768x10^17 seconds remaining, then we just multiply the two numbers to calculate the total mass lost).
Multiplying these two numbers gives 6.78024x10^26 kg. This is the total mass of the Sun that will be converted to energy in the remainder of the Sun's lifetime.
To calculate the percentage we must do: mass lost / original mass of the sun and multiply the value by 100%.
In other words:
((6.78024x10^26)/(2.0x10^30)) x 100% to get: 0.034% (to 2 decimal places).
Hope this helps!