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Functions/363390: What advantage(s) can you see of having a function rule instead of a table of values for a function? Explain.
1 solutions
Answer 259174 by robertb(4012)   on 2010-10-29 06:21:46 (Show Source):
You can put this solution on YOUR website!One of the advantages is , for a function rule (like a formula or equation), the domain is bigger, and thus could be used more precisely and with more versatility to model natural phenomena. Another advantage is, if we restrict ourselves to table of values only, we cannot develop a lot of mathematics around the concept of functions.
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Miscellaneous_Word_Problems/363475: The least and greatest numbers in a list of 7 real numbers are 2 and 20 ,respectively. The median of the list is 6 , and the number 3 occurs most often
in the list.
which of the following could be the average (arithmetic mean) of the numbers in the list ?
I 7
II 8.5
III 10
(A) I only
(B)I and II only
(c) I and III only
(D) II and III only
(E) I, II, and III
1 solutions
Answer 259172 by robertb(4012) on 2010-10-29 06:07:54 (Show Source):
You can put this solution on YOUR website!(E) I, II, and III.
We could have the following arrangement for the numbers:
2,3,3,6,x,y,20, in ascending order. The mean is formed as follows:
 .
If the average is 7, then x+y = 15, which is very much possible for two numbers x and y between 6 and 20.(Take 7 and 8, e.g.) If the average is 8.5, then x+y = 25.5, which again is possible for two numbers between 6 and 20 (take 10 and 15.5, e.g.) If the average is 10, then x+y = 36, which again is possible for two numbers between 6 and 20 (take 17 and 19, e.g.)
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Probability-and-statistics/363476: if j is chosen at random from the set { 4,5.6 }and k is chosen at random from the set { 10,11,12 }. what is the probability that the product of j and k is divisible by 5 ?
1 solutions
Answer 259170 by robertb(4012) on 2010-10-29 05:44:38 (Show Source):
You can put this solution on YOUR website!***if j is chosen at random from the set { 4,5,6 }and k is chosen at random from the set { 10,11,12 }. what is the probability that the product of j and k is divisible by 5 ?***
The answer is 5/9. Just form the "multiplication table" for j and k. The possible products are 40,50,60,44,55,66,48,60,72. Out of the 9 products, 5 are divisible by 5. Hence the answer.
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Rational-functions/363481: The speed of train A is 20mph slower than the speed of train B. Train A travels 230 miles in the same it takes train B to travel 330 miles. Find the speed of each train.
1 solutions
Answer 259169 by robertb(4012) on 2010-10-29 05:37:22 (Show Source):
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Rational-functions/363482: Jack usually mows his lawn in 4 hours. Marilyn can mow the same yard in 6 hours.
How much time would it take for them to mow the lawn together.
1 solutions
Answer 259168 by robertb(4012) on 2010-10-29 05:32:35 (Show Source):
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Probability-and-statistics/363454: A random experiment has sample space S ={a, b, c}. Suppose that P[{a, c}] = 5/8 and P[{b, c}] = 7/8. Use the axioms of probability to find the probabilities of elementary events.
1 solutions
Answer 259154 by robertb(4012) on 2010-10-29 01:17:00 (Show Source):
You can put this solution on YOUR website!P[{a,b,c}] = P[{a,c}] + P[{b,c}] - P[{c}]. Thus  - P[{c}]. Hence P[{c}] = 1/2. Now P[{a,c}] = P[{a}] + P[{c}], so P[{a}] = 1/8. Finally, P[{b}] =  .
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Probability-and-statistics/363430: In Texas 75% of all drivers wear their seat belts.
A) Out of 160 drivers, what is the expected number who are wearing their seat belts?
B) How many drivers will need to be observed in order to be 99.5% certain of observing more than two wearing their seat belts?
Thank you in advance.
1 solutions
Answer 259153 by robertb(4012) on 2010-10-29 01:00:03 (Show Source):
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test/363369: Here is question: find the sum of all multiples of 4 that are between 14 and 523. Thank for help me
1 solutions
Answer 259098 by robertb(4012) on 2010-10-28 21:28:33 (Show Source):
You can put this solution on YOUR website!a1 = 16 and an = 520. Also, an = a1 + (n-1)d = 16 + (n-1)4 = 4n + 12.
We solve for n. 520 = 4n + 12.
4n = 508, or n = 127. By the formula for the sum of an arithmetic series,
 .
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Probability-and-statistics/363372: A recent study of cardiovascular risk factors reports that 30% of adults meet the criteria for hypertension. If 15 adults are assessed, what is the probability that:
a. Exactly 5 meet the criteria for hypertension?
b. None meet the criteria for hypertension?
c. Less than or equal to 7 meet the criteria for hypertension?
1 solutions
Answer 259089 by robertb(4012) on 2010-10-28 21:11:00 (Show Source):
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Probability-and-statistics/363334: In a multiple-choice test, each question has four options. Students will get 5 points for each correct answer; lose 1 point for each incorrect answer; and receive no points for unanswered questions. A student does not know the correct answer for one question. Is it to her advantage or disadvantage to guess an answer? Show your calculations for expected value. Show your work for full credit.
1 solutions
Answer 259084 by robertb(4012) on 2010-10-28 21:03:43 (Show Source):
You can put this solution on YOUR website!The probability of giving a correct answer is 1/4, the probability for a wrong answer is 3/4. If he has to give an answer, his expectation is  . If he doesn't give an answer, his expectation is 0. Therefore it is better to just guess the answer. =)
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Mixture_Word_Problems/363358: A metallurgist needs to make 12.4 lb of an alloy containing 50% gold. He is going to melt and combine one metal that is 60% gold with another metal that is 40% gold. How much of each should he use?
1 solutions
Answer 259078 by robertb(4012) on 2010-10-28 20:53:11 (Show Source):
You can put this solution on YOUR website!0.60x + 0.40(12.4 - x) = 0.50*12.4,
0.60x + 4.96 - 0.40x = 6.2,
0.20x = 1.24,
x = 6.2. He has to mix 6.2 lb of the 60% gold alloy, and the same amount of the 40% gold alloy.
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Points-lines-and-rays/363362: The equation c=$.05m+ $ 4.95 represents the cost (C) of a long didtance telephone call of m minutes.
what is the slope of the line?
what does the slope represent in this situation?
what is the y-intercept (C-intercept)?
what does the y-intercept represent in this situation?
1 solutions
Answer 259072 by robertb(4012) on 2010-10-28 20:47:57 (Show Source):
You can put this solution on YOUR website!The slope of the line is is 0.05. It means that every minute of call costs a nickel. The c-intercept is 4.95, and it means the fixed cost of making a call: you pay $4.95 whether you make a call or not.
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Linear-equations/363351: equation of a line containing the given point and perpendicular to the given line: (4,-3);2x+7y=8
1 solutions
Answer 259050 by robertb(4012) on 2010-10-28 20:21:30 (Show Source):
You can put this solution on YOUR website!The desired equation would have the form  , where c is a constant that is to be determined. To find c, plug in the coordinates of the given point into the desired equation: 7*4 - 2*-3 = c, or 28 + 6 = c, or c = 34. Therefore the eqaution is  .
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Rectangles/363339: The perimeter of a rectangle is 30 inches, and its area is 36 in2. Find its length and width.
1 solutions
Answer 259049 by robertb(4012) on 2010-10-28 20:15:31 (Show Source):
You can put this solution on YOUR website!2l +2w = 30, or l+w = 15. we have l = 15 - w.
Also, area is lw = 36. By direct substitution, (15 - w)w = 36.
 ,
 ,
 ,
w = 3 or w = 12. The rectangle is 3"x 12".
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Polynomials-and-rational-expressions/363343: can you please explain the steps
identify the ploynomial as a monomial, binomial,or none of these
give its degree and leading coefficient
-5x+8
thank you
1 solutions
Answer 259040 by robertb(4012) on 2010-10-28 19:57:49 (Show Source):
You can put this solution on YOUR website!The expression is an example of a BINOMIAL, or a polynomial with 2 terms. The degree is 1 (the highest power of x in the equation), and the leading coefficient is -5 (the coefficient of x.)
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Graphs/363316: Determine whether the two lines are parallel, perpendicular, or neither;
3y + 21= 2x
2y= 16-3x
1 solutions
Answer 259037 by robertb(4012) on 2010-10-28 19:49:24 (Show Source):
You can put this solution on YOUR website!The two lines are perpendicular: the slope of the top equation is 2/3, while the slope of the bottom eqaution is -3/2. The product of the slopes is -1, and hence the conclusion.
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