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richard1234 answered: 5385 problems
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Probability-and-statistics/403119: Winning a race: The odds against Paul Phillips winning the 100 yard dash are 7:2. Determine the probability that a) Paul wins and b)Paul doesn't win. What would the formula be for solving this problem. I know that there are 9 chances that he will win because the sum of 2 and 7. Where do I go from there? I need the formula so I can show my work. Thank you for your help! 1 solutions
Answer 285077 by richard1234(5390) on 2011-02-01 21:10:48 (Show Source):
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Numbers_Word_Problems/403059: I am a number between 10 and 20. My tens digit is 1. Each digit to the right is twice as great as the digit before it. What is the value of the digit in the hundredths place? 1 solutions
Answer 285074 by richard1234(5390) on 2011-02-01 21:07:41 (Show Source):
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Volume/402702: rain which falls onto a flat rectangular surface of length 6 m and width 4 m is collected in a cylinder of internal radius 20 cm. What is the depth of water in the cylinder after a storm in which 1 cm of rain fell?
1 solutions
Answer 284816 by richard1234(5390) on 2011-02-01 07:53:28 (Show Source):
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Equations/402316: write an equation using f for the number of faces, e for the number of edges and v for the number of vertices.
What is the relationship of the number of edges and the number of vertices in a cube? 1 solutions
Answer 284762 by richard1234(5390) on 2011-01-31 22:20:12 (Show Source):
You can put this solution on YOUR website!There is a formula named after Euler that says that F + V - E = 2, for any polyhedron. A cube has six faces, eight vertices, and twelve edges, and satisfies, since 6 + 8 - 12 = 2. An interesting fact is that Euler's formula can be applied to higher dimensions, including 4-, 5-, ... dimensional manifolds.
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Numbers_Word_Problems/402344: The counting numbers are 1,2,3,4, and so on. If the sum of three different, odd counting numbers is less than 10, what is the largest of the three?
CLUE: The answer is less than 9.
1 solutions
Answer 284760 by richard1234(5390) on 2011-01-31 22:15:32 (Show Source):
You can put this solution on YOUR website!The counting numbers 1, 3, 5 add up to 9, which is less than 10. However, if we choose any other set of three distinct counting numbers, the sum would be at least 10 (since we know that {1, 3, 5} has the minimal sum). Therefore {1, 3, 5} is the only such set and the largest of the numbers is 5.
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Travel_Word_Problems/402443: A golf ball is launched upward with an initial speed of 30 m/sec by a golfer atop the Washington Monument, which is 160 m above the ground. How high above the ground will the ball be after 3 sec?
I'm not sure how to set this up. Should I use: distance = rate × time?
1 solutions
Answer 284753 by richard1234(5390) on 2011-01-31 21:56:23 (Show Source):
You can put this solution on YOUR website!Distance = rate*time only works for constant velocity problems. In this problem, we have the acceleration due to gravity.
The formula for determining position given a constant acceleration is  , where a = -9.81 m/s^2,  is the original velocity,  is the original position (this equation is derived using integral calculus). Here, t = 3 s,  = 30 m/s,  = 160 m. Therefore,
 = 205.9 meters
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Miscellaneous_Word_Problems/402565: 1. In this problem, we analyze the profit found for sales of graphic t-shirts. A demand equation (sometimes called a demand curve) shows how much money people would pay for a product depending on how much of that product is available on the open market. Often, the demand equation is found empirically (through experiment, or market research).
a. Suppose a market research company finds that at a price of p = $25, they would sell x = 60 shirts each month. If they lower the price to p = $15, then more people would purchase the shirts, and they can expect to sell x = 75 shirts in a month’s time. Find the equation of the line for the demand equation. Write your answer in the form p = mx + b. Hint: Write an equation using two points in the form (x, p). Show all your work.
A company’s revenue is the amount of money that comes in from sales, before business costs are subtracted. For a single product, you can find the revenue by multiplying the quantity of the product sold, x, by the demand equation, p.
b. Substitute the result you found from part a. into the equation R = xp to find the revenue equation. Provide your answer in simplified form. Show all your work.
The costs of doing business for a company can be found by adding fixed costs, such as rent, insurance, and wages, and variable costs, which are the costs to purchase the product you are selling. The portion of the company’s fixed costs allotted to this product is $600, and the supplier’s cost for a shirt is $18 each. Let x represent the number of shirts.
c. If b represents a fixed cost, what value would represent b? Show all your work.
d. Find the cost equation for the shirt. Write your answer in the form C = mx + b. Show all your work.
The profit made from the sale of shirts is found by subtracting the costs from the revenue.
e. Find the Profit Equation by substituting your equations for R and C in the equation . Simplify the equation. Show all your work.
f. What is the profit made from selling 33 shirts per month? Show all your work.
g. What is the profit made from selling 27 shirts each month? Show all your work.
h. What is the profit made from selling no shirts each month? Interpret your answer. Show all your work.
i. Use trial and error to find the quantity of shirts per month that yields the highest profit. Show all your work.
j. How much profit would you earn from the number you found in part i? Show all your work.
k. What price would you sell the shirts at to realize this profit? Hint: Use the demand equation from part a. Show all your work.
1 solutions
Answer 284736 by richard1234(5390) on 2011-01-31 21:35:44 (Show Source):
You can put this solution on YOUR website!I don't think I or any tutor will answer all 11+ parts to this question...but I'll get you started and you can finish the rest.
To find the linear equation, we have two ordered pairs (25, 60) and (15, 75) (here, the price is the x-variable, however normal demand curves list the number sold as the x-variable). The slope m is equal to  so m = -3/2. To find the y-intercept replace m, as well as an ordered pair to obtain
60 = (-3/2)(25) + b --> 60 = -75/2 + b --> b = 195/2 = 97.5
The demand equation is therefore given by  . You should be able to figure out the rest of the problems. Btw, part i) does not require trial and error, since the revenue is given by px, we have a quadratic equation that we can optimize using the vertex of the quadratic, or by the derivative.
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Linear-equations/401989: tell whether each equation represents direct or inverse variation:
y=80x
xy=80
y=80/x
y/x=80 1 solutions
Answer 284443 by richard1234(5390) on 2011-01-30 22:07:20 (Show Source):
You can put this solution on YOUR website!The first and fourth equations are equivalent, and they represent direct variation because when x increases, y also increases by the same ratio. The second and third equations are equivalent and they represent inverse variation because when x increases, y decreases (and vice versa).
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Word_Problems_With_Coins/396775: Using only quarters, nickels, dimes and pennies--how many ways can I make 0.99? (99 cents) 1 solutions
Answer 284440 by richard1234(5390) on 2011-01-30 21:50:40 (Show Source):
You can put this solution on YOUR website!Note that this is equivalent to finding the number of ways to make 95, 90, 85, ..., 0 cents using quarters, nickels, and dimes since the pennies will be uniquely determined afterwards. Also, we can further reduce this to make 19, 18, 17, ..., 0 cents using 5 cent, 2 cent, and 1 cent pieces (for example, 3 quarters, 1 dime, 2 nickels making 95 cents is equivalent to 3 5-cent pieces, 1 2-cent piece, 2 1-cent pieces making 19 cents). In essence, we have established a bijective function that maps some set of numbers to a set that is a bit easier to count.
Therefore we want to find the number of ways to make 0 cents, 1 cent, ..., 19 cents (using 5-cent, 2-cent, 1-cent pieces), and add them up. Here, I will demonstrate the number of ways to make x cents *without* using a 5-cent piece:
Case 0: We wish to make 0 cents --> 1 way (just use no coins)
Case 1: We wish to make 1 cent --> 1 way 2*0 + 1*1
Case 2: We wish to make 2 cents --> 2 ways 2*1 + 1*0; 2*0 + 1*2
Case 3: We wish to make 3 cents --> 2 ways 2*1 + 1*1; 2*0 + 1*3
Case 4: We wish to make 4 cents --> 3 ways 2*2 + 1*0; 2*1 + 1*2, 2*0 + 1*4
Case 5: We wish to make 5 cents --> 3 ways 2*2 + 1*1, 2*1 + 1*3, 2*0 + 1*5
There is a pattern, which we can prove by a simple induction or modular arithmetic argument, that the number of ways to make k cents increments by 1 every 2 cents. We can generalize and say that the number of ways to make k cents without using a 5-cent piece is  where  represents the floor value of z. Summing up from k = 0 to k = 19,
 +... +  = 110.
Now, suppose  and we wish to count the number of ways to make k cents using exactly one 5-cent piece. We can note that this is analogous to computing the ways of making 0 to 14 (subtracting 5 from all terms). In other words, we have
 + ... +  = 64
Repeat the same with the cases where two 5-cent pieces and three 5-cent pieces are used. Basically, only the bounds are changed to {0, 9}, {0, 4}.
 + ... +  = 30
 = 9
Adding all these values up, we get 110 + 64 + 30 + 9 = 213 ways. Since our function is bijective, we can say that the number of ways to make 99 cents is also equal to 213.
This solution required the use of a bijective function, which is normally not taught in a standard middle/high school curriculum. Here is a Wikipedia article in case you're interested: http://en.wikipedia.org/wiki/Bijection
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Linear-systems/401954: the width of a rectangle is 4 feet less then the lenght. the area is 5ft sqaured whats the legth and width ? 1 solutions
Answer 284411 by richard1234(5390) on 2011-01-30 20:51:07 (Show Source):
You can put this solution on YOUR website!Width = 1 ft, Length = 5 ft. It's possible to do this without the quadratic formula since the only factors of 5 are 5 and 1, which differ by 4. However the surefire way is to use the quadratic formula.
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Equations/401961: i have been working on this problem for quite a while and cant seem to get it right without using a calculator. my question is -3+3y=2y+5. thank you so much. it is very appreciated. 1 solutions
Answer 284409 by richard1234(5390) on 2011-01-30 20:45:28 (Show Source):
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Linear-equations/401645: Please I really need help with this equation
2u-9=7u+15-u-20
Could you show me step by step how to solve it 1 solutions
Answer 284262 by richard1234(5390) on 2011-01-30 08:50:46 (Show Source):
You can put this solution on YOUR website!Combine like terms on both sides to get
2u - 9 = (7u - u) + (15 - 20) = 6u - 5
Add -2u to both sides to get
-9 = 4u - 5
Add 5 to both sides to get
-4 = 4u --> u = -1.
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Equations/401445: Determine whether the ordered pair is a solution of the given equation:
(-2,3); x + 2y = -2
The answer book says Yes....I keep coming up with No.
Please help. 1 solutions
Answer 284209 by richard1234(5390) on 2011-01-29 23:10:23 (Show Source):
You can put this solution on YOUR website!In fact you're right...an ordered pair lies on the function if (and only if) equality occurs. Here, if we replace x = -2 and y = 3,
-2 + 2(3) = -2
-2 + 6 = -2, not true, so the ordered pair doesn't lie on the line.
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