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    hello, i just took it today,anyone remember the question about a 2 litres water tank?
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    Yep, I got 64 or so for (A), 996 I think for (B) and 92.3% I think for the last part of the question...not quite sure on how correct they are though.
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    hey derray do u remember what is the question for (c) i only remember it loses 10 litres on the first day and 10% more on next day? am i right? or it is 0.1% more on next day?
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    (Original post by deryayyy)
    Yep, I got 64 or so for (A), 996 I think for (B) and 92.3% I think for the last part of the question...not quite sure on how correct they are though.
    how do you solve for (b) and (c)?
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    I used the 2000= a +(n-1)d I don't remember a and d, and for c I did a*r, my r was 1.1 because it was increasing at 10% and then I found out what that percentage was from 2000. What about you? What did you get?
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    (Original post by deryayyy)
    I used the 2000= a +(n-1)d I don't remember a and d, and for c I did a*r, my r was 1.1 because it was increasing at 10% and then I found out what that percentage was from 2000. What about you? What did you get?
    for (b), i used Sn=n/2 (2a+(n-1)b) = 2000 because the tank will lose all of its volume on the nth day.
    so 4000=n(20+(n-1)2)
    4000=20n+2n^2-2n
    4000=2n^2+18n
    2n^2+18n-4000=0
    n^2+9n-2000=0
    n= ( -9+sqrt(81-4 x 1 x -2000) ) / 2
    n= 40.4 n= 41 days
    for (c) V lost =sn=a(r^n-1)/r-1
    V lost =Sn=10(1.1^30 -1)/1.1-1
    %V left = (2000-Sn)/2000 x 100%
    i got 17.8%
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    Does anyone remember the exact question? Like including the description they gave at top? At least the description? Please post here. I want to read it again.
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    (Original post by marksman11)
    for (b), i used Sn=n/2 (2a+(n-1)b) = 2000 because the tank will lose all of its volume on the nth day.
    so 4000=n(20+(n-1)2)
    4000=20n+2n^2-2n
    4000=2n^2+18n
    2n^2+18n-4000=0
    n^2+9n-2000=0
    n= ( -9+sqrt(81-4 x 1 x -2000) ) / 2
    n= 40.4 n= 41 days
    for (c) V lost =sn=a(r^n-1)/r-1
    V lost =Sn=10(1.1^30 -1)/1.1-1
    %V left = (2000-Sn)/2000 x 100%
    i got 17.8%
    I got n=41 as well...thank god...i was scared when i got n as 40.44 and i had to cancel my working and do it again. For the percentage, i got 17.8 too.
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    Why are people getting n=996 and the percentage as 92.1????? I'm so scared
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    i got 996 and 92.1% too bcs i think i read that it gets refilled everyday but i am not sure, anyone remembers what the question said?
 
 
 
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