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    Prospectors are drilling for oil. The cost of drilling to a depth of 50m is £500. To drill a further 50m costs £640 and hence the total cost of drilling to a depth of 100m is £1140. Each subsequent extra depth of 500m costs £140 more to drill than the previous 50m.
    a) Show that the cost of drilling to a depth of 500m is £11300.
    b) the total sum of money available for drilling is £76000. Find, to the nearest 50m, the greatest depth that can be drilled.
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    (Original post by Capsfree)
    Prospectors are drilling for oil. The cost of drilling to a depth of 50m is £500. To drill a further 50m costs £640 and hence the total cost of drilling to a depth of 100m is £1140. Each subsequent extra depth of 500m costs £140 more to drill than the previous 50m.
    a) Show that the cost of drilling to a depth of 500m is £11300.
    b) the total sum of money available for drilling is £76000. Find, to the nearest 50m, the greatest depth that can be drilled.

    What seems to be the problem so you ask for help with 12 exclamation marks ...
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    (Original post by TeeEm)
    What seems to be the problem so you ask for help with 12 exclamation marks ...
    I don't know where to start. :confused: I'm sooo confused
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    (Original post by Capsfree)
    I don't know where to start. :confused: I'm sooo confused
    ok what topic do you think is involved here?
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    (Original post by TeeEm)
    ok what topic do you think is involved here?
    Arithmetic series
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    Think about it. It goes up 140 quid every 50M extra. The first 50M = 500 quid, from 50-100 it is 640.. so from 100 to 150 it will be 780... 150 to 200 will be 920... continue that up to 450-500 which is 1760. Add all of the totals, you get 11300.
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    (Original post by Capsfree)
    Arithmetic series
    very good
    they are saying

    first 50 m .......total depth 50m ........... £500
    next 50m ........total depth 100m ..........£(500 +140)
    next 50m ........total depth 150m...........£(500 +140 x 2)
    next 50m ........total depth 200m...........£(500 +140 x 3)


    form an arithmetic progression by identifying the first term and common difference and use the standard formulas
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    (Original post by iMacJack)
    Think about it. It goes up 140 quid every 50M extra. The first 50M = 500 quid, from 50-100 it is 640.. so from 100 to 150 it will be 780... 150 to 200 will be 920... continue that up to 450-500 which is 1760. Add all of the totals, you get 11300.
    quid?
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    (Original post by iMacJack)
    Think about it. It goes up 140 quid every 50M extra. The first 50M = 500 quid, from 50-100 it is 640.. so from 100 to 150 it will be 780... 150 to 200 will be 920... continue that up to 450-500 which is 1760. Add all of the totals, you get 11300.
    Can you use the arithmetic series formula please?
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    (Original post by TeeEm)
    very good
    they are saying

    first 50 m .......total depth 50m ........... £500
    next 50m ........total depth 100m ..........£(500 +140)
    next 50m ........total depth 150m...........£(500 +140 x 2)
    next 50m ........total depth 200m...........£(500 +140 x 3)


    form an arithmetic progression by identifying the first term and common difference and use the standard formulas
    Thanks.
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    (Original post by Capsfree)
    Thanks.
    my pleasure
 
 
 
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