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Math Help - Quiz Correction For Extra Credit

  1. #1
    MarkJames
    Guest

    Quiz Correction For Extra Credit

    My teacher has been hadning back someof our quizes from the previous semester, and i have totally forgotten how to do some of these problems.

    If anyone could help me out, i would deeply appreciate it. I want to get my grade up to an A, so every bit of extra credit we get handed out, im going to do.

    But anyway, here are some o fthe problems off the quiz im having issues with...

    Problem Number: 1
    Solve the following problem.

    An alloy of copper is 10% copper and weighs 25 pounds. A second alloy is 18% copper. How much (to the nearest tenth lb.) of the second alloy must be added to the first alloy to get a 13% mixture.

    _________

    (Answer in Pounds)


    Problem Number: 2
    Solve the following problem.

    An alloy weighing 30 lbs. is 11% tin. The alloy was made by mixing a 15% tin alloy and a 9% tin alloy. How many pounds of each alloy were used to make the 11% alloy?

    ______ lbs. of the 15% alloy and _____ lbs. of the 9% alloy.

    Problem Number: 3
    Solve the following problem.

    Brine is a solution of salt and water. If a tub contains 70 pounds of a 5% solution of brine, how much water (to the nearest tenth lb.) must evaporate to change it to an 7.5% solution?

    ______ lbs. of water must evaporate.

    Problem Number: 4
    Solve the following problem.

    To reduce 16 ounces of a 18% saline solution to a 10% solution, how much distilled water (to the nearest tenth oz.) should a nurse add?

    The nurse should add _____ oz. of distilled water.

    Problem Number: 5
    Choose the right answer.

    Mr. Thompson has been asked to add storage space to a garage. He estimates 6 square feet per individual will be required to meet the needs of 12 people. If the storage space is 15% of the total amount of space required, how much total space does Mr. Thompson have?

    Mr. Thompson had _______ square feet.

    Problem Number: 6
    If a rectangular lot measures 120 ft. x 80 ft., and 10 foot set backs are required from each lot line, how much area is left? If a kennel for 50 dogs requires 12,500 square feet, how many dogs can be accommodated in the small rectangle?

    There will be _______ square feet in the smaller lot.

    The number of dogs allowed is ________. (Use a whole number.)

    Problem Number: 7
    Choose the right answer.

    If you have a rectangular space with dimensions of 180 ft. x 75 ft., and 20,000 square feet is required by 45 cars, do you have sufficient space for 46 cars?

    ___________


    Problem Number: 11
    Solve this problem.

    Two angles are complementary. One contains 20 more than the other. Find both angles.

    The measures of the angles are _________ and _______ degrees.

    Problem Number: 12
    Solve this problem.

    How large is an angle whose supplement is three times its complement?

    The measure of the angle is __________ degrees.

    Problem Number: 13
    Solve this problem.

    An angle is 10 more than the measure of its complement. Find the number of degrees in each angle.

    The angles measure ______ degrees and _______ degrees.

    Hope theres somone out there that could help

    -Thanks, Mark
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by MarkJames View Post
    Problem Number: 1
    Solve the following problem.

    An alloy of copper is 10% copper and weighs 25 pounds. A second alloy is 18% copper. How much (to the nearest tenth lb.) of the second alloy must be added to the first alloy to get a 13% mixture.
    you have 25 lb of alloy which is 10% Cu, so you have 2.5 lb of Cu.

    Now add x lb of the 18% alloy, this contains 0.18x lb of Cu, so the
    new percentage of Cu is:

    (2.5+0.18x)/(25+x)

    which is the mass of Cu divided by the total mass, and we want this
    to be 13% or 0.13, so:

    (2.5+0.18x)/(25+x) = 0.13,

    so:

    2.5 + 0.18x = 0.13(25+x)

    or:

    0.05x = 0.13*25 - 2.5 = 0.75,

    so:

    x = 0.75/0.05 = 15 lb.

    RonL
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  3. #3
    Grand Panjandrum
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    Quote Originally Posted by MarkJames View Post
    Problem Number: 5
    Choose the right answer.

    Mr. Thompson has been asked to add storage space to a garage. He estimates 6 square feet per individual will be required to meet the needs of 12 people. If the storage space is 15% of the total amount of space required, how much total space does Mr. Thompson have?

    Mr. Thompson had _______ square feet.
    Storage space of 6 sq ft per person for 12 people is 12*6=72 sq ft of
    storage space altogether. This is 15% of the total space so:

    0.15*total = 72,

    so:

    total = 72/0.15 = 480 sq ft.

    RonL
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  4. #4
    Grand Panjandrum
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    Quote Originally Posted by MarkJames View Post
    Problem Number: 11
    Solve this problem.

    Two angles are complementary. One contains 20 more than the other. Find both angles.

    The measures of the angles are _________ and _______ degrees.
    Complementary angle are angles which sum to 90 degrees. let the
    smaller angle be u degrees, then the larger is u+20 degrees (you are
    told this) as these are complementary the sum to 90 degrees so:

    u + (u+20) = 90,

    or:

    2u+20 = 90

    2u = 90-20 = 70,

    so:

    u = 35 degrees.

    Problem Number: 12
    Solve this problem.

    How large is an angle whose supplement is three times its complement?

    The measure of the angle is __________ degrees.
    Angle are supplementary if they add to 180 degrees, so if our angle
    is u degrees, its supplement is 180-u degrees, and its complement is
    90-u degrees.

    So we are told that the supplement is three times its complement so:

    180-u = 3(90-u),

    which you must solve for u to find the answer.

    RonL
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  5. #5
    MarkJames
    Guest
    Wow thnx bro, helped ALOT
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