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  1. #1
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    SI

    A person spends a part of amount of $20,000 for buying. 40% of the remaining amount is given at 6% interest and the rest money is given at 10% interest. If the total interest the person gets is $1250, then what is the amount he used for buying?
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  2. #2
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    I do not understand what you posted.
    Could you ask someone to help you with your English?
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  3. #3
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    Quote Originally Posted by bluffmaster.roy.007 View Post
    A person spends a part of amount of $20,000 for buying. 40% of the remaining amount is given at 6% interest and the rest money is given at 10% interest. If the total interest the person gets is $1250, then what is the amount he used for buying?
    Quote Originally Posted by Wilmer View Post
    I do not understand what you posted.
    Could you ask someone to help you with your English?
    My Interpretation

    1. A person gets $20,000
    2. This person then spends an amount of money
    3. 40% of the remainder attracts 6% interest
    4. 10% of the remainder (from step 2) attracts 10% interest.

    ----------

    Let x be the amount he spends and y be the amount which gets interest

    y = 20,000-x

    40% of y gets 6% interest: 0.4y(1.06)^n
    60% of y gets 10% interest: 0.6y(1.10)^n

    0.4y(1.06)^n + 0.6y(1.10)^n = 1250

    If we assume n is over one period of time (usually annually) so that will cancel

    0.424y+0.66y = 1250

    1.084y = 1250

    <br />
y = 1153.1365

    x = 20000-y = 20000-1153.1365 = \$18846.86
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  4. #4
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    Hello, bluffmaster.roy.007!

    I interpreted it differently . . .


    A person spends a part of amount of $20,000 for buying.
    40% of the remaining amount is given at 6% interest
    and the rest of the money is given at 10% interest.

    If the total interest the person gets is $1250,
    then what is the amount he used for buying?

    The person has $20,000.
    He spend x dollars for buying.
    He has 20,\!000-x dollars remaining.

    40% of this remainder is: . 0.40(20,\!000-x) dollars.
    This earns 6% interest: . I_1 \:=\:(0.06)(0.40)(20,\!000-x)\:=\:480 - 0.024x

    60% of the remainder is: . 0.60(20,\!000-x) dollars.
    This earns 10% interest: . I_2 \:=\:(0.10)(0.60)(20,\!000-x) \:=\:1200 - 0.06x


    The total interest is $1250: . (480-0.024x) + (1200 - 0.06x) \:=\:1250

    We have: . 0.084x \:=\:430 \quad\Rightarrow\quad x \:=\:\frac{430}{0.084} \:=\:5119.047619


    Therefore, he used $5,119.05 for buying.

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  5. #5
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    alternate solution......

    Mr sorobon is rite..........
    lets see how eazy it is..........consider x be the amount remainin...
    that is x=20,000-amount used for buying.

    40% of remaining amount x gets 6%interest
    that is......(0.4)(0.06)(x)

    and for second interest (0.6)(0.1)(x)

    together they make 1250$=0.024x+0.06x

    x=1250/0.084=14880.1

    so amount used for buying is 20,000-x

    and that is 5119.9$....
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