IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => GCE AS & A2 Level => Math => Topic started by: cashem'up on February 06, 2010, 06:42:06 pm
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Jack is saving for a new car which will cost $29000 . He saves by putting $400 a mmonth into a savings account which gives 0.1% interest per month . After how many months will hee be able to buy his car.
pg 40 chapter 3 question8 exc 3C P2
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When I come back
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Jack is saving for a new car which will cost $29000 . He saves by putting $400 a mmonth into a savings account which gives 0.1% interest per month . After how many months will hee be able to buy his car.
a GEOMetric series
S_n=a(1-r^n)/(1-r)
29000=400(1-1.001^n)/(1-1.001)
1-1.001^n=29000/400*(-0.001)=-.0725
1.001^n=1+0.0725
n=ln(1,0725?/ln(1.001)=70.027
so n=71