density of water = mass/volume
d = 25 g/25cm3
d = 1g/cm3
Density of water is the same for all 3 values = 1g/cm3.
Average density of water = (1g/cm3 + 1g/cm3 + 1g/cm3)/3
= 1g/cm3
Standard deviation:
where symbol a is the standard deviation, xi is each value from the population, u is the mean and N is the size of population.
values are all = 1g/cm3
mean = average = 1g/cm3
N = 3 values
standard deviation = [(1g/cm3-1g/cm3)^2 + (1g/cm3-1g/cm3)^2 + (1g/cm3-1g/cm3)^2]/3
standard deviation = 0
%error = 0%