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A boat weighs 1500 lb more than its motor ... |
2005-10-17 |
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From Dimitri:
A boat weighs 1500 lb more than its motor and 1900 lb more than its trailer. Together the boat and motor weigh five times as much as the trailer. How much does the boat weigh?
Answered by Penny Nom. |
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Arrays |
2005-10-17 |
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From Danette:
My son's fourth grade workbook is asking him to draw four possible arrays for 72 marbles.
I don't understand what they mean
Answered by Penny Nom. |
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Divisibility by each of the first ten counting numbers |
2005-10-17 |
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From Simon:
determine smallest positive integer that is divisible by each of the first ten counting numbers
Answered by Penny Nom. |
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A random sample |
2005-10-16 |
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From Stu:
If I have a set of data points (14 to be exact)of unknown pedigree from a large population, what tests can I apply to see if they constitute a random sample from the large population?
Answered by Andrei Volodin and Penny Nom. |
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2x - 5x + 6.3 = -14.4 |
2005-10-16 |
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From Leslie:
How do we solve 2x - 5x + 6.3 = -14.4
Answered by Penny Nom. |
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How many gallons will it hold? |
2005-10-16 |
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From Scott:
I am building a pond and need to convert the cubic dimensions into gallons in order to know what size fountain pump to purchase.
My pond is 1 foot deep x eight feet long x three feet wide.
How many gallons will it hold?
Answered by Penny Nom. |
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What is the sum of the measures of the angles of a decagon? |
2005-10-15 |
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From Dianna:
What is the sum of the measures of the angles of a decagon?
Answered by Penny Nom. |
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How many pixels are there to an inch? |
2005-10-15 |
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From Fred:
I want to know how many pixels there are to an inch.
Answered by Penny. |
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How would I find the length of the radius? |
2005-10-15 |
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From Stace:
If given the length of a chord (121") and the distance from the midpoint of the arc to the midpoint of a chord (12"), how would I find the length of the radius?
Answered by Penny Nom. |
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The area of an irregular semi-circle |
2005-10-14 |
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From Bob:
Is there a way to compute the area of an irregular semi-circle i.e. one in which the arc length is not determined by the diameter; and is therefore not technically any part circular - yet still possessing an arched side?
Answered by Penny Nom. |
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Determine the height |
2005-10-14 |
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From Paul:
if you know the distance to the base and the angle to the top how can you determine the height
Answered by Penny Nom. |
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The coefficient of thermal expansion for steel |
2005-10-14 |
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From Jim:
Is the following statement true?
“The coefficient of thermal expansion for steel is 0.00000645in/in/deg. Doesn't sound like much but when you run out the numbers it comes to .405504 ft/mile/deg. Still doesn't sound like much, only about 5". Then multiply by 40 degrees and you get a piece of rail that has grown by 16.22 feet in that one mile. It's not at all unusual for the rail temp to go from say, 40 deg to 80 deg on a spring or fall day. Remember that on a sunny day, the rail temp can be significantly higher than the air temp as well."
I ran the math and came up with an answer closer to 16 inches, instead of 16 feet. Which is closer to being correct?
Answered by Penny Nom. |
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Simultaneous equations |
2005-10-13 |
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From Daniel:
5x + 3y = 22
4x - 7y = -20
Answered by Penny Nom. |
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The bathtub curve |
2005-10-13 |
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From David:
My father asked me to submit a question about the so-called 'bathtub
curve'. If you cut a bathtub in half lengthwise down it's middle, the
edge of the tub would describe the 'bathtub curve' which can be used
to demonstrate typical failure rates of products. This curve is
characterised by high initial (infant mortality) failure rates at
it's beginning, which drop quickly to a very low level. Failures then
increase gradually to the "end of life" stage where the failure rate
takes off dramatically again.
If anyone in the math department knows about the so-called 'bathtub
curve' my father would really appreciate the equation.
Answered by Chris Fisher and Edward Doolittle. |
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Means of sample means |
2005-10-12 |
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From Fareeha:
A population consists of six numbers 1,2,3,4,5,6
a) How many different samples of two numbers can be selected with replacement? and list them.
b) Calculate the mean and standard deviation of the population
b2) Calculate the mean and standard deviation of the mean of the samples.
c) Find the standard error of your estimated mean in question b2 and compare with the estimated standard deviation in b2.
Answered by Penny Nom. |
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