in adding the measurements 11.074m, 18.2m and 16.943m, what should be the number of significant figures in the result

The average atmospheric pressure on earth is approximated as a function of altitude by the relation patm = 101.325 (1 − 0.02256z)5.256, where patm is the atmospheric pressure in kpa, and z is the altitude in km with z = 0 at sea level. determine the approximate atmospheric pressures at atlanta (z = 306 m), denver (z = 1610 m), mexico city (z = 2309 m), and the top of mount everest (z = 8848 m).

Chi walked 100 meters in 5 minutes. she took another 15 minutes to walk another 400 meters to reach her house. what is her average speed?

For two variables in a direct proportion, what is the result of doubling one variable?