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josmiceli answered: 9815 problems
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Expressions-with-variables/529648: My question is whats substition I keep hearing about? How does it work? Can you tell me how to solve a problem using substition? 1 solutions
Answer 349645 by josmiceli(9817) on 2011-11-10 14:31:32 (Show Source):
You can put this solution on YOUR website!Sure.
Suppose you have 2 equations with
2 unknowns. It definitely should be
solvable, and one way is by substitution.
Say the equations are
(1) 
(2) 
-----------------------
From(1), I get
(1) 
Now I will Substitute this value of 
into equation (2)
(2) 
(2) 
(2) 
(2) 
(2)

The solutions are
(10,0) and (5,-5)
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Probability-and-statistics/529602: If two cards are drawn from a standard 52 card deck without replacement, in how many different ways is it possible to obtain a heart on the first draw and an ace on the second? 1 solutions
Answer 349640 by josmiceli(9817) on 2011-11-10 13:33:12 (Show Source):
You can put this solution on YOUR website!I'd get a 2nd opinion on this, but here's my view:
There are 13 ways that you can draw a heart first
Having drawn the heart, there are 4 ways to draw
an ace, so there are  ways to get
this combination. But what if the 1st card is the
Ace of hearts. Then there are only 3 ways to draw
an Ace. So I have to subtract the one combination
that I counted twice, that is Ace of hearts and
Ace of hearts again.
There are then 51 ways to draw a heart and then
an Ace. Hope I got it.
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percentage/529617: how to do percentages. 1 solutions
Answer 349635 by josmiceli(9817) on 2011-11-10 13:17:16 (Show Source):
You can put this solution on YOUR website!You need to fix in your mind that
per cent means "per one-hundred"
Think of the % sign as saying: you need to
divide this number by 100.
-------------------------
Suppose I say 67%
% means to divide it by 100, so
what I really have is 67/100 = .67
------------------------
Another problem you will see is:
convert .67 to a percent
The algebra for this is
.67 = x/100
This says: .67 is what percent ?
Multiply both sides by 100
67 = x, so
67/100 = 67 percent
Hope this helps
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Age_Word_Problems/529334: Mrs Sabado is 6 times as old as her daughter May. Next year her age will be equal to the square of her daughter's age. Find the present age. 1 solutions
Answer 349558 by josmiceli(9817) on 2011-11-09 21:41:22 (Show Source):
You can put this solution on YOUR website!Let  = Mrs. Sabado's age now
Let  = May's age now
given:
(1) 
(2) 
----------------------
(2) 
Substitute (1) into (2)
(2) 
(2) 
(2) 
Either  or 
If  ,
(1) 
(1) 
------------
If  , then
(1) 
(1) 
This says they are both newborns, which
is impossible, so
24 is Mrs. Sabado's age now
4 is May's age now
check:
(2) 
(2) 
(2) 
(2) 
OK
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Inequalities/529309: Need assistance with this, i cant figure it out. It's driving me mad. Thank you.
Lena is choosing between two exercise routines.
In routine #1, she burns 25 calories walking. She then runs at a rate that burns 18 calories per minute.
In routine #2, she burns 49 calories walking. She then runs at a rate that burns 14 calories per
minute.
For what amount of time spent running will routine #1 burn fewer calories than routine#2? Use t for the number of minutes spent running, and solve your inequality for t. 1 solutions
Answer 349543 by josmiceli(9817) on 2011-11-09 21:14:36 (Show Source):
You can put this solution on YOUR website!Let  = minutes spent running
given:
Routine #1
Calories burnt = 
Routine #2
Calories burnt = 
------------------------
Let calories burnt = 
The question is:
for what values of  is

Subtract  from both sides

Subtract  from both sides

or, what is the same,

So, for all values of  minutes spent running,
The calories burnt using routine #1 are less than
the calories burnt using #2
Here's a plot of routine #1 and #2:

The bottom line is routine #1. You can see that when
 as it should, and they meet at
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Money_Word_Problems/529293: Cliff had a total of $100,000 to invest. He put some of the money in Bank A that paid 4% interest and the rest in Bank B which paid 5% interest. After a year, the amount of interest he earned was $4850. How much money did Cliff invest in Bank A? Also provide a step by step procedure on how to get the answer. 1 solutions
Answer 349538 by josmiceli(9817) on 2011-11-09 20:51:27 (Show Source):
You can put this solution on YOUR website!Let  = amount invested @ 4%
Let  = amount invested @ 5%
given:
(1) 
(2) 
--------------------
(2) 
Multiply both sides of (1) by 
and subtract (1) from (2)
(2) 
(1)

and, since
(1) 
(1) 
(1) 
Cliff invested $15,000 in bank A
check answer:
(2) 
(2) 
(2) 
(2) 
OK
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Money_Word_Problems/529205: John invested $8000 for one year, part at 8% interest and the rest at 10%. If John earned $700 in interest, how much is in each account? 1 solutions
Answer 349524 by josmiceli(9817) on 2011-11-09 19:31:33 (Show Source):
You can put this solution on YOUR website!Let  = amount invested @ 8%
Let  = amount invested @ 10%
given:
(1) 
(2) 
-----------------
(2) 
(2) 
Multiply both sides of (1) by 
and subtract (1) from (2)
(2) 
(1)

and, since
(1) 
(1) 
(1) 
$5,000 is the amount invested @ 8%
$3,000 is the amount invested @ 10%
check answer:
(2) 
(2) 
(2) 
(2) 
OK
|
Rate-of-work-word-problems/528667: One computer takes 21 minutes longer than a second computer to do the job. Working together these computers can do the same job in 10 minutes. How long would it take each computer working alone to do the same job? 1 solutions
Answer 349388 by josmiceli(9817) on 2011-11-09 03:31:07 (Show Source):
You can put this solution on YOUR website!Add their rate of doing jobs to get
their rate together.
Let  = the time in minutes for the 2nd computer
to finish the job.
Then  is the time for the 1st computer
to do the job
 is the 1st computer's rate
 is the 2nd computer's rate
 is their rate working together

Multiply both sides by

Complete the square
 ( ignore the negative square root )

It will take the 1st computer 35 min
It will take the 2nd computer 14 min
check:

Multiply both sides by

OK
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Polynomials-and-rational-expressions/528696: This question is driving me up the wall. It has to be answered only in fractions and not in decimals.
Two thirds of two is what part of three
or put another way, 2/3 of 2 is x (what) part of 3.
I'm not sure, but the answer is 4/9, but how is the problem solved (step by step) to arrive at the figure of say 4/9 or whatever?.
I'm 80+ and still doing ok, no Alzheimer yet..ha-ha, many thanks for any help. 1 solutions
Answer 349386 by josmiceli(9817) on 2011-11-09 03:00:39 (Show Source):
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Permutations/528682: I am having a really hard time trying to figure out this question please help,all I know so far is that I should use permutation, but I don't know how:
Question:
A class consists of 60 ladies and 40 men. In how many ways can a president, vice president, treasurer and secretary be chosen if the treasurer must be a lady, the secretary must be a man and the student may not hold more than one office?
Thank you 1 solutions
Answer 349384 by josmiceli(9817) on 2011-11-09 02:27:51 (Show Source):
You can put this solution on YOUR website!I'll take shot at it, but you might want to get
a 2nd opinion
Since the treasurer must be a lady, there are
60 different ways that office can be filled
Since the Secretary must be a man, there are
40 ways that office can be filled.
There are  different ways
that the 2 offices can be held
-------------------------
Once the Treasurer and Secretary offices have
been filled, there are 
people left to fill President and Vice-President
There are  different ways to fill
these 2 offices ( M or F doesn't matter )
-------------------------
The 4 offices can then be filled in
 different ways.
( I lost calculator, you can finish )
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Equations/528541: In a fifth-grade class of 16 students, one-half of the students showed up early, one-fourth of the students showed up on time and one-eighth showed up late. How many students were absent? 1 solutions
Answer 349322 by josmiceli(9817) on 2011-11-08 20:25:00 (Show Source):
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Evaluation_Word_Problems/528539: The class average on a test is exactly 83. take away the best score and the average is 82. There are 16 students in the class, what is the best score?
x/16=83-x/16??? 1 solutions
Answer 349319 by josmiceli(9817) on 2011-11-08 20:20:17 (Show Source):
You can put this solution on YOUR website!Let  = sum of scores of all 16 students in class
Let  = the highest score of the 16 students
With all the students in class:
(1) 
With highest score taken away:
(2) 
------------------
This is 2 equations and 2 unknowns, so it's solvable
(1) 
(2) 
Substitute (1) into (2)
(2) 
(2) 
Can't find my calculator- you can finish
|
Travel_Word_Problems/528170: A man rode a bicycle for 12 miles and then hiked and additional 8 miles. The total time for the trip was 5 hours. If his rate when riding a bicycle was 10 miles per hour faster than his rate walking, what was each rate? 1 solutions
Answer 349174 by josmiceli(9817) on 2011-11-08 12:06:59 (Show Source):
You can put this solution on YOUR website!Let  = rate walking
Let  = rate biking
given:
 mi/hr
 hrs
--------------------
biking:

walking:

-------------------
By substitution:

By substitution again:

Substitution again:

Completing the square:
 ( can't use the negative root )
and

His speed biking was 12 mi/hr
His speed walking was 2 mi/hr
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Probability-and-statistics/528157: in a certain population, 30% of the women are married and 40% of the men are married. what percent of the total population in married? round answer to the nearest tenth of a percent. assume that one woman is married to one man and that each couple resides in this population- 1 solutions
Answer 349162 by josmiceli(9817) on 2011-11-08 11:33:28 (Show Source):
You can put this solution on YOUR website!Let  = number of women in population
Let  = number of men in population
Because the married women and married
men are paired with each other, I can say

I am asked to find:

To the nearest 1/10 of a percent,
34.3% of the population is married
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Linear-systems/528039: How do you solve for y and x ? Like my promblem says solve for y right? So they gave me the promblem 4y + 12 = -3(2x-4), could you help me with this promblem? 1 solutions
Answer 349139 by josmiceli(9817) on 2011-11-08 03:59:02 (Show Source):
You can put this solution on YOUR website!What they mean is:
Get y all by itself on one side of the equation
It doesn't really matter which side
---------------------------
You do this by doing the same thing to
both sides of the equation, which leaves
the equation unchanged
----------------------------

Subtract  from both sides

Now divide both sides by

This is OK, but you can finish by
multiplying out

Now you have
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Miscellaneous_Word_Problems/527745: Juan wants to make a trail mix that contains 40% pecans. He has a bag of trail mix that has only 25% pecans at home and another bag that contains only pecans. How much of each should he mix together to make a 16-oz bag of trail mix that contains 40% pecans? 1 solutions
Answer 349013 by josmiceli(9817) on 2011-11-07 18:06:17 (Show Source):
You can put this solution on YOUR website!He ends up with
 ounces of pecans
Let  = ounces of 25% mix needed
Let  = ounces of 100% mix needed
given:
(1) 
(2) 
Multiply both sides of (2) by
 . Then multiply both
sides of (1) by  and subtract
(1) from (2)
(2) 
(1)

and, since
(1) 
(1) 
12.8 ounces of 25% mix are needed
3.2 ounces of 100% mix are needed
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Rate-of-work-word-problems/527717: SOPPOSE 4 PEOPLE CAN PAINT A HOUSE IF THEY WORKK 3 DAYS EACH. HOW LONG WOULD IT TAKE OF A CREW OF 5 PEOPLE TO PAINT THE HOUSE ? 1 solutions
Answer 349012 by josmiceli(9817) on 2011-11-07 17:46:20 (Show Source):
You can put this solution on YOUR website!I assume all these people work at the same rate
4 people working 3 days can paint 1 house
1 person takes 4 times as long to paint the house, so
1 person takes 12 days to paint the house
5 people will take 1/5 of that time to paint the house
5 people will take 12/5 days, or 2.4 days to paint the house
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