# Thread: Quiz Correction For Extra Credit

1. ## 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.

_________

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

2. Originally Posted by MarkJames
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

3. Originally Posted by MarkJames
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

4. Originally Posted by MarkJames
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

5. Wow thnx bro, helped ALOT