Theory question 107
Commercial ArithmeticA man bought 5 reams of duplicating paper, each of which was supposed to contain 480 sheets. The actual number of sheets in the packets were 435, 420, 405, 415 and 440.
(a) Calculate, correct to the nearest whole number the average percentage error for the packets of paper
(b) If the agreed price for a full ream was N35.00, find, correct to the nearest naira, the amount by which the buyer was cheated.
Show the model answer
Model answer
(a) Expected = 5 × 480 = 2400 sheets; actual = 2115; shortfall = 285
Average percentage error = 285/2400 × 100 = 11.875% ≈ 12%
(b) Cost of one sheet = N35 ÷ 480; amount cheated = 285 × 35/480 = N20.78 ≈ N21
Explanation
The average of the five percentage errors gives the same 11.875% because every ream should have 480 sheets.