Question

Santana Office Supplies record the number of times their five photocopiers break down.

The graph above shows the number of breakdowns for their photocopiers during 2011.
Which of the following statements about photocopier A1 is correct compared to the other photocopiers?
A1 had just under a half the number of breakdowns compared to photocopier B3
A1 had just under 50% of the breakdowns compared to photocopier B2
A1 had more than 25 extra breakdowns compared to photocopier B1
A1 had 6% less breakdowns than photocopier A2

Answer 1

The xerographic process, which was invented by Chester Carlson in 1938 and developed and commercialized by the Xerox Corporation, is widely used to produce high-quality text and graphic images on paper. Because Xerox marketed the first plain-paper copiers, photocopying machines made by other companies are sometimes referred to as "Xerox machines" by those who dont realize its a misuse of the companys trademark. In addition, the xerographic process is actually used to make both copies and prints.

Carlson originally called the process electrophotography. Its based on two natural phenomena: that materials of opposite electrical charges attract and that some materials become better conductors of electricity when exposed to light. Carlson invented a six-step process to transfer an image from one surface to another using these phenomena. First, a photoconductive surface is given a positive electrical charge. The photoconductive surface is then exposed to the image of a document. Because the illuminated sections (the non-image areas) become more conductive, the charge dissipates in the exposed areas. Negatively charged powder spread over the surface adheres through electrostatic attraction to the positively charged image areas. A piece of paper is placed over the powder image and then given a positive charge. The negatively charged powder is attracted to the paper as it is separated from the photoconductor. Finally, heat fuses the powder image to the paper, producing a copy of the original image.

Carlsons first image, produced on October 22, 1938, was created with negatively charged yellowish moss spores (lycopodium) on a sulfur-coated zinc plate that had been positively charged by rubbing it with a handkerchief. Todays copiers and printers have automated and refined all the steps, moving paper at speeds of more than 250 feet a minute, digitally creating and exposing images, and producing images in a rainbow of colors.