Question from http://www.sgforums.com/forums/2297/topics/334900
The normal price of a roll of film for 36 photographs is $8.99.
The normal price of printing 36 photographs is $17.65 for each roll of film.
(a) Show that the cost of each photograph is 74 cents.
(b) Shop A offers '4 rolls of film for the price of 3'.
The price of printing 36 photographs remains at $17.65 for each roll of film.
Kim bought 4 rolls of film at Shop A and had the photographs printed there.
Calculate how much each photograph cost her, to the nearest cent.
(c) Shop B kept the price of each roll of film at $8.99. If offered a 20% off the normal price for printing the photographs.
Sue bought one roll of film at shop B and had the photographs printed there.
Calculate how much each photograph cost her, to the nearest cent.
(d) Ali decided to buy 4 rolls of film at Shop A and have his photographs printed at Shop B.
Calculate the percentage reduction in cost of each of his photographs compared to the cost in (a).
Answer:
(a) Cost of each photograph = ($8.99 + $17.65) / 36 = $0.74 (shown)
(b) Cost of each photograph = ($8.99 * 3 + $17.65 * 4) / (36 * 4)
= $95.57 / 144
= $0.677
= $0.68 (to nearest cent)
(c) Cost of each photograph = ($8.99 + $17.65 * 0.8) / 36
= $23.11 / 36
= $0.641
= $0.64 (to nearest cent)
(d) Cost of each photograph = ($8.99 * 3 + $17.65 * 4 * 0.8) / (36 * 4)
= $83.45 / 144
= $0.579
= $0.58 (to nearest cent)
Percentage reduction = (0.74 - 0.58) / 0.74 * 100%
= 0.16 / 0.74 * 100%
= 21.62%
= 21.6% (3 s.f.)
