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A four-digit positive integer |
2009-09-04 |
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From TRACEY:
I AM A FOUR-DIGIT POSITIVE INTEGER SUCH THAT THE SUM OF MY DIGITS IS 18 AND MY DIGITS REVERSED ARE EXACTLY FOUR TIMES GREATER THAN MYSELF. WHAT NUMBER AM I?
Answered by Robert Dawson. |
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Simplify |
2009-09-04 |
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From Sarah:
How do you simplify:
(x-4)^3?
Answered by Robert Dawson. |
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Airline overbooking |
2009-09-03 |
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From Nikita:
An airline company knows that 8% of it's passengers will not show up for their scheduled flights. A plane has 175 seats.
a) What is the probability that 10 passengers or fewer will not show up?
b) What is the probability that 10 to15 passengers will not show up?
c)What is the probability that exactly 10 passengers will not show up?
d) What is the probability that more than 19 passengers will not show up?
Answered by Robert Dawson. |
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Nickels and dimes |
2009-09-03 |
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From MATTHEW:
mike has 3 times as many nickels as Larry has dimes. Mike has 45 cents more than Larry. How much money does Mike have?
Answered by Penny Nom. |
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A 30% markup |
2009-09-02 |
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From Lisa:
Ok i want to mark a products up 30%, I would take 5.00X3o%,but my boss does it another way I have yet to figure out he takes cost divided by 70% or something like that I am so lost can you help? PLEASE
Answered by Victoria West and Penny Nom. |
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Show your work |
2009-09-02 |
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From Gerald:
We have a 6th grade student who can solve math problem successfully without showing her work. The teacher thinks it is not fair that she doesn't show her work and the other have to and do. What sort of classroom accommodation(s) would you recommend for this type of student. It would seem to be a popular problem since there are many student who think more global than sequential.
Answered by Victoria West, Penny Nom and Robert Dawson. |
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Normal Distribution |
2009-09-02 |
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From Nikita:
Scores on a college exam are known to be normally distributed with a standard deviation of 20. If the top 3% have scores in excess of 200, what is the mean score?
Answered by Robert Dawson. |
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The intersection of two graphs |
2009-09-02 |
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From Jaqueline:
Find the points of intersection of the graphs of the equations
x^(2 )+ y^2=25 and 2x + y = 10
Answered by Penny Nom. |
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Is -100 degree angle an acute angle? |
2009-09-02 |
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From Nazrul:
Is -100 degree angle an acute angle? Please explain. Here -100<90.
Answered by Robert Dawson. |
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Price increases and decreases |
2009-09-02 |
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From craig:
I work for an industry that bases it price increases and decreases on commodity pricing - Customer get confused on how/why we calculated new prices due to movement in the market -
Price go up x% for every $10 of movement in the market -
For this example-
Movement went down by $30 and it is 2% for every $10 - so price decrease was 6%.
Customer's price is currently $100.
We say - $100/1.06= new price of $94.3
Customer says - $100*.94= new price of $94.
They don't understand that if board went back up $30 which would be 6% increase, they wouldn't be back at $100 if they multiplied on the price decrease.
$94*1.06=$99.64 vs. $94.3*1.06=$100 (Back to the original price)
What is the best way to explain to customer besides using this example?
Any help or info is appreciated.
Craig
Answered by Victoria West. |
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Nickels, dimes and quarters |
2009-09-02 |
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From danielle:
In changing a $5 bill, Sarah received nine more dimes than nickles and seven fewer quarters than dimes. How many coins of each type did she receive?
Answered by Penny Nom. |
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Zero Angle |
2009-09-01 |
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From Nazrul:
Is zero degree an acute angle? Please explain.
Answered by Janice Cotcher. |
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Arithmetic Sum & Sequence |
2009-09-01 |
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From Alice:
Find the 24th term of this sequence
6.8,8.0,9.2...
Find the sum of the first 21 terms
Answered by Janice Cotcher. |
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What is 8 tons in exponential form? |
2009-09-01 |
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From Tyler:
what is 8 tons in exponential form
Answered by Penny Nom. |
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Cardinality of infinite sets |
2009-09-01 |
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From Brian:
I was reading an answer to a question on your site regarding infinite sets (http://mathcentral.uregina.ca/QQ/database/QQ.09.01/carlos1.html), and I think they may have got the answer wrong.
I his example, he claims that the set of real numbers BETWEEN 0 AND 1 is larger than the set of positive integers.
Please correct me if I am wrong, but I believe those two sets are -- pardon the expression -- equally infinite. For any integer, there is a corresponding real number between 0 and 1, and vice versa.
For instance, using the decimal as a "mirror", you can create a mirror image of any real number between 0 and 1 as an integer (i.e. 0.1234 gets mirrored as the integer 4321 -- I could write it out algebraically, if you want, but you get my point)
Am I wrong?
Thanks,
Brian
Answered by Victoria West. |
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