Math help please

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Trackrunner220

Math help please

Post by Trackrunner220 » Sun Oct 11, 2009 11:42 pm

I am having some difficulty with these word problems if anyone can help out...with work or explanation


1)Your car gets 25 miles per gallon. You start off on a 200 mile trip with 3/4 of a tank and finish the trip with 1/5 a gas tank left. How much further could you drive before you run out of gas.

2)You make monthly deposits to your savings accounts. The first month you deposit $100. Each deposit is one dollar more than the previous one. How much will you have deposited after 25 years?

3) tom takes 3 hours to paint a room and Bill takes 4 hours. How much time will they have to paint a room if they work together

4) A= a,c,d,e,f,g,h
B= b,d,g,h
C= a,b,c,g.
What combination of set operations on these sets will produce the set {b|


5)50 people like A, 50 people like B and 50 people like C. There are 100 people in all amongst A,B,C. Of these, 20 people like A and B. 20 people like B and C. 20 people like A and C. How many people like A and B but not C.(A and B overall)


Before you think im lazy and making you guys do my work I did 45 other problems and got the other answers...the closest to an answer I have here, but I think I am wrong is...

1) 50 miles
2)74900
3)1 hour 40 min
4) B and C (this i am just not sure)
5)I got either the answer 80 or 50.


Any math help?

Tinman
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Math help please

Post by Tinman » Sat Oct 17, 2009 5:56 pm

Trackrunner -

I have been very busy, so I didn't notice you had posted questions in this part of the forum. Anyway, I have a couple of minutes now to look at your questions. The first problem looks like a matter of determining what part of the tank has been used during 200 miles of travel and (then) extrapolating the total mileage one could travel with a full tank of gas.

First adjust the given fractions to the same (lowest common) denominator. The easiest is 20. Therefore, 3/4th is is 15/20ths and 1/5th is 4/20ths.

Second, subtract and you get 11/20ths of a tank used to travel 200 miles.

Third, divide 200 miles by 11/20ths to get the total miles one could travel on a full tank of gas. That turns out to be 363.6364 miles.

Fourth, subtrack the total possible miles (363.6364) from the actual miles traveled (200) and you get 163.6364 or ~163.6 miles. Of course, this depends upon no changes in the rate of burning fuel.
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Math help please

Post by Tinman » Sat Oct 17, 2009 6:31 pm

Trackrunner -

The second question requires a "running total" formula. I am rusty at classroom math, so I went to Excel on my computer and input data for 3 lines and dragged it to 300 months, which is 25 years. Then, I summed the running total column and it showed me $74,850. I highlighted the months (X column) to the total in each adjacent box (y column) and then used the scatter plot section of Excel's stats. I used a polynomial equation and the result was this: y=.5X^2 + 99.5x

You can input, therefore, any number of months you want and the result will be the running total to that point.

Example: 120 months, which is 10 years, would be as follows:

y = .5(120^2) + 99.5(120)

y = 7,200 + 11,940

y = $19,140
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Math help please

Post by Tinman » Sat Oct 17, 2009 6:45 pm

Trackrunner -

For equestion # 3:

Again, I don't remember the fancy formal way of doing math problems like this, but I almost always can figure out the answer using logic. To answer the question, I input an arbritrary number of square feet each painter would need to paint 120 s.ft. - just something tangible. To paint 120 square feet in 3 hours, Tom would have to pain 40 s.ft. per hour. To pain 120 s.ft. in 4 hours, Bill would have to pain 30 s.ft. per hour.

Next, I add 40 s.ft. per hour to 30 s.ft. per hour to determine how much the two would paint; if they worked together (at the same time). That's 70 s.ft. per hour.

Then, I divided the total s.ft. (120) by 70 (the combined per hour rate) and the result was 1.714286 hours to pain 120 s.ft.

To check the result, I input a different total s.ft. amount (99) and the answer was the same. Therefore, Tom and Bill can paint (together) a given space in ~1.7143 hours, if they have no variations in painting rate.
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Math help please

Post by Tinman » Sat Oct 17, 2009 7:12 pm

Problem # 5:

I think the answer is 20. I deduce the the cross-over is 40 for any combination (A+B or B+C or A+C). Therefore, any singular letter (A,B, or C) should be 10. Combinining A+B, therfore would equal 20.

I haven't done this type of math question (problem) since I was a sophomore in high school - and that was 1982, so forgive me if I am off.
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Math help please

Post by ATimmins » Fri Nov 13, 2009 10:02 pm

Im a big advocate of answering word problems with outragous but factual answers and/or more information required.

So here it goes.

1)Your car gets 25 miles per gallon. You start off on a 200 mile trip with 3/4 of a tank and finish the trip with 1/5 a gas tank left. How much further could you drive before you run out of gas.

Answer: Not very far is living in hawaii.


2)You make monthly deposits to your savings accounts. The first month you deposit $100. Each deposit is one dollar more than the previous one. How much will you have deposited after 25 years?

Answer: Due to current economy, there is a good chance you will have nothing.

3) tom takes 3 hours to paint a room and Bill takes 4 hours. How much time will they have to paint a room if they work together

Answer: Due to tom recently having an affair with bill's wife, those 2 will probably not complete the room

4) A= a,c,d,e,f,g,h
B= b,d,g,h
C= a,b,c,g.
What combination of set operations on these sets will produce the set {b|

Answer: Did you hear about bill's wife?

5)50 people like A, 50 people like B and 50 people like C. There are 100 people in all amongst A,B,C. Of these, 20 people like A and B. 20 people like B and C. 20 people like A and C. How many people like A and B but not C.(A and B overall)

Answer: Due to this tally being done in Florida i question is accuracy and refuse to continue.
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First = 13:38
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