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Geometry_Word_Problems/584918: One evening 1500 concert tickets were sold. Tickets cost $20 for pavillion seats and $15 for lawn seats. Total receipts were $27,500. How many tickets of each type were sold? 1 solutions
Answer 372972 by solver91311(16868) on 2012-03-09 15:53:56 (Show Source):
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Surface-area/584883: Prism A and prism B are similar. If prism A has length 5 feet and width 8 feet and prism B has length 7.5 feet, what is the width of prism B? 1 solutions
Answer 372971 by solver91311(16868) on 2012-03-09 15:51:51 (Show Source):
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Points-lines-and-rays/584911: Hi id like some help with this question here:
A triangle has vertices A(11,1) B(3,6) and C(3,-4)
Find an equation of the line that is parallel to AB and contains point C.
I think it was (-2,-2)(3,-4) 1 solutions
Answer 372960 by solver91311(16868) on 2012-03-09 15:22:19 (Show Source):
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Triangles/584906: a right isosceles triangle has legs of length 12cm. what is the length of its hypotenuse? Express your anwser in simples radical form 1 solutions
Answer 372959 by solver91311(16868) on 2012-03-09 15:17:58 (Show Source):
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Miscellaneous_Word_Problems/584850: Two sandboxes, one with black sand and one with white sand, each contain the same amount of sand. You scoop a full bucket of black sand and pour it into the white sand. Trying to avoid doing your algebra homework, you stir the mixture for hours and hours until the black and white sand are perfectly mixed. You then scoop a full bucket of the mixed sand and pour it into the black sand so that both sandboxes once again have the same amount of sand.
Which is greater, the amount of black sand added to the white sand or the amount of white sand added to the black sand, or are they equal? Be sure to fully explain your reasoning with a mathematical example. 1 solutions
Answer 372954 by solver91311(16868) on 2012-03-09 15:05:17 (Show Source):
You can put this solution on YOUR website!
Let represent the amount of black sand originally in the black sandbox, and let represent the amount of black sand in one full bucket of black sand. Likewise, let and represent analogous quantities of white sand.
Before anything happens, there are units of black sand in the black sandbox and units of white sand in the white sandbox. After the one bucket of black sand is taken from the black sandbox and added to the white sandbox, the black sandbox will contain units of black sand and the white sandbox will contain units of white sand plus units of black sand.
After the white sandbox has been "perfectly" mixed and a full bucket of mixed sand is taken out, the bucket will (because the mixture is "perfect") contain exactly units of mixed sand and the formerly white but now mixed sandbox will contain units of mixed sand (because half a bucket each of white and black were taken away -- the white from what was already there at the start and the black from the whole bucket of black that was added).
When the bucket of mixed is added back to the black sandbox, now there is in the formerly black sandbox; half a bucket of black being returned leaving a deficit of half a bucket of black and half a bucket of new white sand that has been added.
So the amount of black added to the white is equal to the amount of white added to the black.
Super Double Plus Extra Credit:
Let's say you didn't bother spend the "hours and hours" to get the "perfect" mixture. Instead, you just dump the bucket of black sand into the white sandbox and then scoop up a bucketful of the white sandbox contents at random such that anywhere from 0 to 100% of the bucket contains black sand. After you dump the contents in the black sandbox, answer the "Which is greater..." question again.
John

My calculator said it, I believe it, that settles it
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Sequences-and-series/584818: My grade in a certain math class is determined by three tests. My highest test score will count for 50%
of my grade and my lowest for 20%; the "middle" test score will count for 30%. I must have a weighted
average of 60 in order to pass the class. If I have already earned scores of 70 on my first two tests,
what is the lowest score I can earn on the third test for which I will still pass the class? 1 solutions
Answer 372923 by solver91311(16868) on 2012-03-09 13:07:20 (Show Source):
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Travel_Word_Problems/584819: How much gas would it take to go 144 miles in a van 1 solutions
Answer 372897 by solver91311(16868) on 2012-03-09 11:40:46 (Show Source):
You can put this solution on YOUR website!
144 divided by the number of miles per gallon achieved by that particular van. The achieved mpg is effected by many factors: The size and type of engine, weight of the loaded vehicle, the material condition of the vehicle, including the engine and drive train, the inflation of the tires, the road conditions, the average speed over the trip, the particular driver's skill (or lack thereof), etc., ad infinitum, ad nauseum. In other words, even though there is no such thing as a stupid question asked by a student, you just got closer than anyone I have ever known.
John

My calculator said it, I believe it, that settles it
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Numeric_Fractions/584363: i do not understand this problem at all and i dont understand what im suppose to do on it... can you please explain to me? the problem is: A brick is 1 7/8 in. high Mortar that is 3/8 in. thick is spread on each row of bricks. How many rows of bricks are needed to reach the top of a 7 1/2-ft doorway? Please try to respond to this for me by tomorrow... my homework is due tomorrow and I really want to be able to know how to do this. Thank you so much for taking your time. 1 solutions
Answer 372763 by solver91311(16868) on 2012-03-08 15:16:54 (Show Source):
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Probability-and-statistics/584299: Someone flips 15 biased coins once. The coins are weighted such that the probability of a head with any coin is 0.85.
(a) What is the probability of getting exactly 14 heads?
(b) What is the probability of getting at least 14 heads?
(c) What is the probability of getting exactly 3 tails?
Would I use the equation p= n!/(r!)(n-r)* p^r q^n - r 1 solutions
Answer 372742 by solver91311(16868) on 2012-03-08 13:36:09 (Show Source):
You can put this solution on YOUR website!
Yep:
The probability of successes in trials where is the probability of success on any given trial is given by:
Where is the number of combinations of things taken at a time and is calculated by
For part (a) you want:
Calculation Hint:
For part (b) you want the probability of exactly 15 plus the result of part (a):
Calculation Hint: and , hence:
Part (c) is just straightforward fill in the numbers, get out the calculator, and crunch noting that the probability of a tail is 1 minus the probability of a head (save for that very, very tiny probability that the coin lands on its edge):
On the other hand you can save yourself a boatload of arithmetic drugery if you open up a spreadsheet (Excel under Windows or Numbers on a Mac, they both work the same), pick a convenient empty cell, and type in:
Part (a)
=BINOMDIST(14,15,0.85,false)
Part (b)
=BINOMDIST(14,15,0.85,false) + BINOMDIST(15,15,0.85,false)
Alternatively you could enter:
=1 - BINOMDIST(13,15,0.85,true)
Part (c)
=BINOMDIST(3,15,0.15,false)
John

My calculator said it, I believe it, that settles it
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