Explanations:
In all the years Total number of mobiles manufactured by company C–1 =(59+65+68)×1000 = 192000 Total number of mobiles manufactured by company C–2 =(62+67+72)×1000 = 201000 Total number of mobiles manufactured by company C–3 =(68+71+74)×1000 = 213000 Total number of mobiles manufactured by company C–4 =(59+62+ 65)×1000 = 186000 Hence company C–4 manufactured the least number of mobiles across all the years.