The following table shows the mass of toxins, in hundredths of a gram, in these samples. Mass (/0.01g) 0– 4– 11– 17– 20–30 No. 10 g samples XXXXXXXXXXa Draw a cumulative frequency curve to illustrate...

The following table shows the mass of toxins, in hundredths of a gram, in these samples. Mass (/0.01g) 0– 4– 11– 17– 20–30 No. 10 g samples 2 19 23 3 3 a Draw a cumulative frequency curve to illustrate the data. b Use your curve to estimate, correct to 2 decimal places: in the interquartile range is the range of the middle 80%. c It was found that toxins made up between 0.75% and 2.25% of the mass of n of these samples. Use your curve to estimate the value of n. d Make an assessment of the variation in the percentage of toxic material in these samples. Can you suggest any possible reasons for such variation? 13 A 9-year study was carried out on the pollutants released when biomass fuels are used for cooking.