Answer: 1044 kPa
Explanation: To find the total pressure of a system, you add up all the partial pressures. 5.00+4.56+356+678=1043.56, but since you need to account for significant figures it is 1044.
In addition, the amount of significant figures is the number with the smallest amount of decimal places. In this case you have no decimal places, since 356 and 678 have no decimal places. Remember that for the numbers 0-4 you round down and 5-9 you round up.
