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Recent problems solved by 'edjones'

edjones answered: 7568 problems
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Polynomials-and-rational-expressions/472674: To determine the number of deer in a game presurve, conservationists catch 697 deer and tags them. Later 408 deer are caught; 204 of them are tagged. How many deer in the presurve? 1 solutions Answer 324059 by edjones(7569)   on 2011-07-21 03:06:31 (Show Source): You can put this solution on YOUR website! 204/408=1/2 the deer are tagged. 697 deer are 1/2 the deer in the preserve. There are 697*2=1394 deer in the preserve. . Ed

Polynomials-and-rational-expressions/472667: The speed of train A is 14mph slower than the speed of train B. Train A travels 190miles in the same time it takes train B to travel 260miles. What is the speed of each train? 1 solutions Answer 324057 by edjones(7569)   on 2011-07-21 03:02:00 (Show Source): You can put this solution on YOUR website! Let b=the speed of b and a=speed of a. b=a+14 t=time, s=speed, d=distance t=d/s d/s=d/s because the time of travel of each train is equal. 190/a=260/(a+14) 190(a+14)=260a 190a+2660=260a 70a=2660 a=38 mph b=52 mph . Ed

Probability-and-statistics/472698: Please help me. A word consist of 5 consonants and 4 vowels. Three letters are selected at random. What is the probability of having more than one vowel? 1 solutions Answer 324053 by edjones(7569)   on 2011-07-21 02:45:04 (Show Source): You can put this solution on YOUR website! nCr=combination of n things taken r at a time.=n!/((n-r)!*r!) Assuming that the letters are chosen without replacement: ((4C2 * 5C1) + (4C3))/9C3 =((6*5)+4)/9C3 =34/84 =17/42 the probability of having more than one vowel. . Ed

test/472637: 3 less then the total of a number and 20 1 solutions Answer 324050 by edjones(7569)   on 2011-07-21 02:33:21 (Show Source): You can put this solution on YOUR website! x+20-3=x+17

Probability-and-statistics/472614: Can someone please help with this problem. A bag contains 6 purple marbles, 7 azure marbles and 10 orange marbles. What is the chance of drawing a purple marble? If a purple marble is drawn then placed back into the bag, and a second marble is drawn, what is the probability of drawing an orange marble? Give solutions exactly in reduced fraction form. 1 solutions Answer 324047 by edjones(7569)   on 2011-07-21 02:26:52 (Show Source): You can put this solution on YOUR website! 6+7+10=23 marbles in the bag. . What is the chance of drawing a purple marble? 6/23 . If a purple marble is drawn then placed back into the bag, and a second marble is drawn, what is the probability of drawing an orange marble? 10/23 . Ed

Numbers_Word_Problems/472618: Consider the numbers 1,2,3 and 5. If the same number is added to each of the numbers, it is found that the ratio of the first new number to the second is the same as the ratio of the third new number to the fourth. Find the number. 1 solutions Answer 324044 by edjones(7569)   on 2011-07-21 02:22:06 (Show Source): You can put this solution on YOUR website! Let x be the number that is added. (x+1)/(x+2)=(x+3)/(x+5) (x+1)(x+5)=(x+3)(x+2) x^2+6x+5=x^2+5x+6 x=1 . Ed

Polynomials-and-rational-expressions/472665: x^2-9/3-x Simplify by removing factors of 1? 1 solutions Answer 324041 by edjones(7569)   on 2011-07-21 02:14:59 (Show Source): You can put this solution on YOUR website! (x^2-9)/(3-x) =(x-3)(x+3)/-(x-3) =-(x+3) . Ed

logarithm/472704: Value of Log(2+4) 1 solutions Answer 324038 by edjones(7569)   on 2011-07-21 02:08:29 (Show Source): You can put this solution on YOUR website! log(6)

Probability-and-statistics/472642: A number cube is rolled and a coin is flipped. If the number cube shows and odd number, or the coin shows tails, or both, you get 6 points. If neither event occurs, you get 4 points. What is the expected value of this game? 1 solutions Answer 324035 by edjones(7569)   on 2011-07-21 02:03:51 (Show Source): You can put this solution on YOUR website! 1/2 * 1/2 = 1/4 of the time the number of the die will be even and the coin will show heads and you get 4 pts. 3/4 of the time you get 6 pts. 3/4 * 6 + 1/4 * 4 =9/2 + 1 =11/2 = 5.5 points, the expected value of the game. . Ed

Probability-and-statistics/472644: There are twelve cars in a parking lot on a very cold day. Suppose the probability of any one of the cars not starting is 0.13. What is the probability that exactly three of the cars do not start? Round answer to the nearest thousandth 1 solutions Answer 324027 by edjones(7569)   on 2011-07-21 01:49:56 (Show Source): You can put this solution on YOUR website! p=.13, q=.87 nCr=12C3=220 Coefficient 220*p^3*q^9=.138 . Ed

Rate-of-work-word-problems/472655: how long dus ti take in plane to get froom lawrence,ma to largo,fl? 1 solutions Answer 324025 by edjones(7569)   on 2011-07-21 01:43:20 (Show Source): You can put this solution on YOUR website! it dee pens

Permutations/472664: Dear math teacher, I really need help with the following word problem: There are 4 hooks on a wall. In how many ways can 3 coats be hung on them, one coat on a hook? I solved it several times and was kind of sure of an answer but my book says 24, and I got 12. Here is how I did it: 4 times Permutation of taking 3 coats and hanging them one at a time because we have 4 hooks. That gives me 12 ways. I also drew a picture of coat 1, coat 2, and coat 3, and started hanging each coat on hook 1, 2, 3, and 4 making a tree below each coat. Each tree gave me 4 ways to hand a coat on a hook, and for 3 coats, I simply added 4 + 4 + 4 ways = 12 ways. So, I got the same answer twice. But then, I did permutation of taking 4 hooks and hanging 3 coats on them and I got 16 ways but this does not make sense because units to the left of permutation must match the units to the right of permuation and I have 4 hooks to the left and 3 coats to the right, so I knew that's is the wrong approach. This kind of reassured me that the first two approaches are correct. Please help me figure out this problem. I would really appreciate it. Thank you so much. And have a wonderful day. 1 solutions Answer 324023 by edjones(7569)   on 2011-07-21 01:38:40 (Show Source): You can put this solution on YOUR website! nPr=permutation of n things taken r at a time.=n!/(n-r)! 4!/(4-3)!=4!=24 . Ed . 123. 12.3 1.23 .123 132. 13.2 1.32 .132 213. 21.3 2.13 .213 231. 23.1 2.31 .231 312. 31.2 3.12 .312 321. 32.1 3.21 .321 . The decimal point is the empty hook in each set of 4 numbers. It could be replace by 0 if you like. As you can see there are 24 ways just as the formula predicts. . Ed

Functions/472677: If you have f(x)=x-2x over zero whats your answer I thought it would be 0 1 solutions Answer 324019 by edjones(7569)   on 2011-07-21 01:17:49 (Show Source): You can put this solution on YOUR website! f(x)=(x-2x)/0 is undefined or meaningless. As the denominator approaches zero the fraction approaches infinity. . Ed

logarithm/472683: ln(x)-ln(4)=5 1 solutions Answer 324017 by edjones(7569)   on 2011-07-21 01:08:34 (Show Source): You can put this solution on YOUR website! ln(x)-ln(4)=5 e^ln(x)/e^ln(4)=e^5 x/4=e^5 x=4e^5 . Ed

Expressions-with-variables/472686: x^2 / x^3+7x = ? 1 solutions Answer 324016 by edjones(7569)   on 2011-07-21 01:03:09 (Show Source): You can put this solution on YOUR website! x^2 / x^3+7x =x^2 / x(x^2+7) = x / x^2+7 . Ed

test/472690: Solve 9x+4=2x+8 1 solutions Answer 324015 by edjones(7569)   on 2011-07-21 00:57:36 (Show Source): You can put this solution on YOUR website! 9x+4=2x+8 7x=4 Subtract 2x+4 from each side x=4/7 divide each side by 7 . Ed

test/472200: Multiply 3(p+1)= 1 solutions Answer 323786 by edjones(7569)   on 2011-07-20 01:36:10 (Show Source): You can put this solution on YOUR website! 3(p+1)=3p+3

Age_Word_Problems/472204: Maria is m years old. Sara is 5 years younger than Maria and 3 years older than Irina. What is the sum of the ages of all 3 girls? A) 3m + 8 B) 3m + 2 C) 3m - 2 D) 3m - 8 E) 3m - 13 THanks! 1 solutions Answer 323784 by edjones(7569)   on 2011-07-20 01:17:22 (Show Source): You can put this solution on YOUR website! sara=m-5 irina=m-8 m+m-5+m-8=3m-13 E . Ed

Travel_Word_Problems/472202: Mr. Ivanov drove a total of 800 miles on a trip. If his vehicle averaged 5 miles per gallon of diesel fuel and diesel fuel costs and average of $0.25 per gallon, how much did he spend on fuel for this trip? A) $25.00 B) $40.00 C) $50.00 D) 160.00 E) $200.00 Thanks! 1 solutions Answer 323783 by edjones(7569)   on 2011-07-20 01:12:47 (Show Source): You can put this solution on YOUR website! 800/5=160 gal .25*160=$40.00 . Ed

Percentage-and-ratio-word-problems/472197: An hour long test has 100 problems. If a student completes 20 problems in 20 minutes, how many seconds does he have on average for completing each of the remaining problems? Thanks! 1 solutions Answer 323782 by edjones(7569)   on 2011-07-20 01:10:15 (Show Source): You can put this solution on YOUR website! 100-20=80 problems remain 60-20=40 minutes remain 80/40 = 2 problems/minute or 30 seconds on average for completing each of the remaining problems. . Ed

Complex_Numbers/472195: can someone help me please? im really stuck simplify the complex fraction. 3/x + 1 + 1/x over 2/x + 1 + 3/x 1 solutions Answer 323781 by edjones(7569)   on 2011-07-20 01:04:25 (Show Source): You can put this solution on YOUR website! 3/x + 1 + 1/x = 4/x + 1 = (4+x)/x . 2/x + 1 + 3/x = 5/x + 1 =(5+x)/x . (4+x)/x / (5+x)/x =(4+x)/x * x/(5+x) =(4+x)/(5+x) . Ed

Probability-and-statistics/472185: On a certain day the number of books on 40 shelves in a library were noted and grouped as shown. Find the mean number of books on the shelf and the standard deviation # of books # of shelves 30 to under 35 4 35 to under 40 6 40 to under 45 10 45 to under 50 13 50 to under 55 5 55 to under 60 2 a) range b) median c) 9th percentile d) Percentile rank of 450 km/h e) Interquartile range 1 solutions Answer 323780 by edjones(7569)   on 2011-07-20 00:57:45 (Show Source): You can put this solution on YOUR website! 2 4 5 6 10 13 . a)13-2=11 . b)(5+6)/2=5.5 . e) Q1=(n+1)/4=(6+1)/4=7/4=2 The 2nd rank number is 4 Q3=3(n+1)/4=3*7/4=5 The 5th rank number is 10 inter quartile range = Q1-Q3=10-4=6 . Ed

Probability-and-statistics/472170: the data shows there is a mean flood of a river of +9.0 feet above flood stage with a dispersion of 5.0 feet around the mean flood level. this means if the mean is 9.0 then the range can be from 4.0 above floor stage to 14.0 above flood level. If this is calculated based on 100 years worth of flood measurements, then how would Ifigure out the flood level of a "1000" year flood. would the flood level still be the same in 1000 years or would it be different? Can i figure out the "1000" year flood level from this information or do I need more information to calculate. thanks! 1 solutions Answer 323774 by edjones(7569)   on 2011-07-20 00:06:27 (Show Source): You can put this solution on YOUR website! for the 100 yr flood. (area under the normal curve greater than .01 has a z of 2.3263) . For the 1000 yr flood: (area under the normal curve greater than .001 has a z of 3.09) (x-9)/2.116=3.09 x-9=6.5 x=15.5 ft . Ed

Probability-and-statistics/472029: For Faculty Appreciation Day, the Faculty Club Lunch Room asked each faculty member to leave a business card in a container. At the end of lunch a card would be drawn, and that faculty member would be given free lunches for a week. Eighty-eight faculty left a card, including 5 mathematics faculty, 11 history faculty, and 2 chemistry faculty. Find the probability of the following. (to three decimal places.) 1 solutions Answer 323768 by edjones(7569)   on 2011-07-19 23:15:02 (Show Source): You can put this solution on YOUR website! No question.

Permutations/472026: A test consists of 30 problems and students are told to answer any 10 of these questions. In how many different ways can they choose the 10 questions? 1 solutions Answer 323767 by edjones(7569)   on 2011-07-19 23:13:55 (Show Source): You can put this solution on YOUR website! nCr=combination of n things taken r at a time=n!/((n-r)!*r!) =30!/(20!*10!) =30045015 ways . Ed

Probability-and-statistics/472028: Three people are selected at random from five females and nine males. Find the probability of the following. (to three decimal places.) 1 solutions Answer 323766 by edjones(7569)   on 2011-07-19 23:09:24 (Show Source): You can put this solution on YOUR website! Huh?

Probability-and-statistics/472041: Question: A battery is defective with probability 0.3. What is the probability that in a pack of 8 batteries: 1) Exactly 2 are defective 2) At most 2 are defective? (hintL at most = less than or equal to) 3) More than 2 are defective? 4) What is the expected number of defective batteries in the 8-pack? 5) What is the standard deviation of the number of defective batteries in the 8-pack? 1 solutions Answer 323763 by edjones(7569)   on 2011-07-19 23:04:52 (Show Source): You can put this solution on YOUR website! n=8, p=.3, q=.7 . 4)E(x)=np=8*.3=2.4 . 5) . 1) nCr=8C2=28 coefficient 28*p^2*q^6=.2965 . Ed

test/472043: My problem is 14x to the 4th Y to the second over 21x to the third y to the third 1 solutions Answer 323762 by edjones(7569)   on 2011-07-19 22:55:13 (Show Source): You can put this solution on YOUR website! (14x^4y^2)/(21x^3y^3) =2x/3y . Ed

Square-cubic-other-roots/472050: =x-2 What I have so far: x^2+2x-8/x = (x-2)(x-2) 1 solutions Answer 323761 by edjones(7569)   on 2011-07-19 22:49:54 (Show Source): You can put this solution on YOUR website! =x-2 x^2+2x-8/x = (x-2)(x-2) x^2+2x-8/x = x^2-4x+4 x^2+2x-8=x^3-4x^2+4x x^3-5x^2+2x+8=0 (x+4)(x-2)(x+1)=0 x=2 The only answer. . Ed

Probability-and-statistics/472059: Each of the seven digits from the number 9,31353 is written on a different card if a card is selected at random from the seven cards, what is the probability of drawing a card that shows a 9,3,or 1? Please provide detail steps. Thanks in advance. 1 solutions Answer 323760 by edjones(7569)   on 2011-07-19 22:38:55 (Show Source): You can put this solution on YOUR website! There are only 6 digits in the number you provided.

Probability-and-statistics/472071: ????? If one check in 10,000 is forged, 3% of all checks are postdated, and 70% of forged checks are postdated, find the probability that a postdated check is forged.(to five decimal places.) 1 solutions Answer 323758 by edjones(7569)   on 2011-07-19 22:35:00 (Show Source): You can put this solution on YOUR website! Out of 100,000 checks 10 are forged and 7 of the 10 are post dated. Out of 100,000 checks 3,000 are post dated. 7/3000=.00233 the probability that a postdated check is forged. . Ed