C1 2017 4 Edexcel

4

(a) The number produced in week 12 is 140 + 11d (note that the number produced in week n is 140 + (n - 1)d), so:

140 + 11d = 206

So:

11d = 66

Giving:

d = 6

(b) The number produced up to week 12 is given by:

\dfrac {12} 2 (206 + 140) = 6 \times (346) = 2076

Then for 40 weeks, only 206 are produced, so the number produced over the remaining 40 weeks is 40 \times 206 = 8240

Adding these the total number of bicycles produced in the 52 week period is 10316.

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