Two laboratories are each given 30 samples over the course of a year to measure the concentration of a pollutant that has a known concentration of 250 ppb. Form histograms of the measured concentrations and comment on the measurement accuracies of the two labs:

Lab A: 232, 234, 236, 237, 237, 239, 241, 241, 243, 243, 244, 246, 246, 246, 246, 247, 247, 248, 248, 248, 249, 249, 251, 251, 251, 251, 252, 254, 256, 256 Lab B: 241, 243, 243, 244, 244, 244, 246, 246, 247, 247, 247, 248, 248, 249, 249, 249, 251, 251, 251, 252, 252, 253, 253, 253, 254, 254, 256, 256, 258, 259