Cumulative percentage of random projections with apparent ellipticity lower than or equal to a given value ϵ_e for the models with an S0b primary galaxy (left panels) and with an S0c primary galaxy (right panel). The dotted lines mark the values corresponding to 50% and 100% of all projections in each model, as a reference. Color-coding for the left panels: black: S0b primary galaxy. Red: mass ratio 6:1, short pericentre, primary S0b. Orange: mass ratio 6:1, long pericentre, primary S0b. Olive green: mass ratio 6:1, short pericentre, primary S0b. Dark green: mass ratio 9:1, short pericentre, primary S0b. Blue: Mass ratio 18:1, short pericentre, primary S0b. Purple: mass ratio 18:1, long pericentre, primary S0b. Color-coding for the right panel: black: S0c primary galaxy. Olive green: mass ratio 6:1, short pericentre, primary S0c, direct orbit. Light green: mass ratio 6:1, short pericentre, primary S0c, retrograde orbit. (This figure is available in color in electronic form.)