A girl saves money over a period of 200 weeks. She saves 5p in Week 1, 7p in Week 2,
9p in Week 3, and so on until Week 200. Her weekly savings form an arithmetic
sequence.
(a) Find the amount she saves in Week 200.
(3)
(b) Calculate her total savings over the complete 200 week period.
Your AS has a = 5 and d = 2
term(200) = a + 199d = 5 + 2(199) = 403
sum(200) = 100(5+403) = 40800
or
sum(200) = 100(2a + 199d) = 100(10+398) = 40800