







A linear relationship 
20161016 

From Bianca: x represents the number of hours since 8am. y represents the number of children the school nurse has seen during the school day. The nurse has seen 3 children by 8am and 27 children by noon.
How many children has the nurse seen at 2pm?
If the nurse has seen 18 children, what time is it? Answered by Penny Nom. 





Archimedes, Euclid and "Circular Reasoning" 
20151115 

From Ron: I have read about Archimedes and his work with sphere in cylinder and cone in cylinder and the volume relationships. Did he or any others also extend this to regular based polygon based regular like pillars, and columns? The ratio of 1/3 to 1 whole holds true with all regular based columns as example: a regular pyramid having a regular hexagon base inside a regular hexagon column of equal height. Answered by Chris Fisher. 





A relation on a collection of sets 
20130204 

From raji: suppose R be a non empty relation on a collection of sets defined by ARB if and only if A intersection B is nullset.then.....the correct answer is R is symmetric and not transitive...my doubt is how it is symmetric Answered by Penny Nom. 





Percent as a fractional relationship 
20130114 

From Kenneth: What does the following indicate?
"A percent is another way of expressing the ratio or fractional relationship
of two numbers."
I know what a ratio is, but the term "fractional relationship" confuses me.
I thank you for your reply. Answered by Penny Nom. 





A linear relationship 
20100622 

From Laura: The monthly cost of driving a car depends on the number of miles driven. Lynn found that in May it cost her $300 to drive 480 miles and in June it cost her $460 to drive 800 miles.
Question: Express the monthly cost C as a function of the distance driven d, assuming that a linear relationship gives a suitable model. Answered by Robert Dawson. 





A linear relationship 
20100224 

From Mel: This table shows the linear relationship between an aeroplane's height (above sea level) and the outside air temperature.
h (cm) 
120 
340 
480 
600 
1040 
T (degrees C) 
14.28 
12.96 
12.12 
11.4 
8.76 
Find the gradient and vertical intercept of the function. Write the formula for T. Answered by Penny Nom. 





The domain, range and inverse of a relation 
20100108 

From Nazrul: Given that A={2,1,0,1,2}, S={(x,y): x belongs to A, y belongs to A and y^2=x}. How can I find the domain and range of the relation S. What is the inverse relation of S. Please show me the process in details.
Thank you. Answered by Penny Nom. 





Domain and range 
20090911 

From Aubrey: I'm supposed to "state the domain/range of each of the following relations" and it's totally not making sense...
Examples:
{(x,y) : x = square root of y}
{(x,y) : y = x + 1, x is some even integer}
Thanks in advance!!
Aubrey Answered by Robert Dawson. 





An equivalence relation 
20090422 

From syed: D is the relation defined on Z as follows:
Z is an integer
For all m,n E Z, m D n if and only if 3 l (m^2  n^2).
Find out whether the above relation satisfies to reflexive , Symmetric & transitive?
Is it an equivalence? Answered by Robert Dawson. 





Find an expression for the nth term 
20090220 

From Dawn: Find an expression for the nth term:
x= 1 2 3 4...n
y=11 8 5 2...?
I think it's a linear relation but don't know the equation that goes with it. Answered by Stephen La Rocque. 





An equivalence relation 
20080827 

From Francesca: In this problem we are told to find out if the given set is an equivalence relation or not.
{(x,y) such that 4 divides xy}. What I am confused about is whether or not for instance if I picked (1,5) as a part of the set whether I could put in (5,1) as well or whether that would be wrong. Thanks! Answered by Victoria West. 





Equivalence relation 
20080319 

From Hmod: State with reasons, whether the relation R on N X N given by mRn
if m and n have difefrent remainders on division by 2 is an Equivalence
relation Answered by Victoria West. 





Growth factor and growth rate 
20080213 

From william: what is the difference between growth factor and growth rate? Answered by Stephen La Rocque and Harley Weston. 





A relationship between numbers 
20080124 

From Robyn: Study these problems: ? 2=4 ? 5=25 ? 9=81
1. Explain what ? means (hint there are two answers).
2. What number is equal to ? 6
3. What number does ? 12 represent? Answered by Stephen La Rocque and Penny Nom. 





What is the relationship between 0/6, 2/4, 4/2, 6/0? 
20080117 

From Olugbenga: What is the relationship between 0/6, 2/4, 4/2, 6/0? Answered by Penny Nom. 





Relations and functions 
20070816 

From virginia: determine whether each relation is a function provide reasons for identifying relation
(3, 4) (5, 9) (9, 9) (2, 3)
(0, 0) (0, 1) (1, 4) (2, 4)
(2, 1) (4, 5) (8, 4) (1, 0)
(8, 3) (8, 0) (7, 7) (4, 7) Answered by Steve La Rocque. 





Equivalence relations 
20070718 

From jim: Determine whether the given relation is an equivalence relation on the set. Describe the partition arising from each equivalence relations.
1. x is Related to y in Real number if lxl=lyl.
2. n is Related to m in Z+ if n and m have the same number of digits in the usual base ten notation.
Let n be a particular integer in Z+. Show that congruence modulo n is
an equivalence relation on Z. Answered by Harley Weston. 





What makes a relation a function? 
20070321 

From san: What makes a relation a function? Answered by Haley Ess. 





Making and using equations 
20060830 

From Brooke:
write an equation to model the relationship between these variables. Define the variables you use, and refer to your notes for a variety of formats of equations we have studied this year.
week 1: 3 birds infected
week 2: 15 birds infected
week 3: 75 birds infected
week 4: 375 birds infected
Answered by Stephen La Rocque. 





A recurrence relation 
20030319 

From Becky: Solve this recurrence relation, with the initial conditions.
A1 = 10 A2 = 100 An = 10a n1 + 29a n2 Answered by Penny Nom. 





Two problems 
20021014 

From Eva:
a) How many different equivalence relations can be defined on the set X={a,b,c,d}? b)Show that 6 divides the product of any 3 consecutive integers. I know it is true that 6 divides the product of any 3 consecutive integers. However, i have problem showing the proof. Answered by Leeanne Boehm and Penny Nom. 





Equivalence relations on a set of cardinality n 
20020706 

From Siddhartha: what is the no. of equivalence and transitive relations on a set of cardinality n? Answered by Penny Nom. 





Functions and relations 
20020425 

From Erin: Here's a few math problems that might drive a person insane ;)  If 2f(x)  3f(1/x) = x^2 what is f(2)?
 What are the domain and range of the following relations?
 x^2  4y^2 = 25
 4x^2 + 9y^2 = 36
 The port of Swan Harbor is 200km away from Merry Town Inlet on a bearing of N50E from Merry Town. A ship leaves Merry Town at 8am and sails N15W at 15 km/h. At the same time, a second ship leaves Swan Harbour on a course of S80W at 20km/hour. How close, to the nearest km, are the two ships at 13:00?
 Prove the identity. 1+sinx + cosx/ 1sinx + cosx = 1+sinx / cosx
Answered by Penny Nom. 





Linear regression 
20010801 

From A student and a mother: My mom is taking a correspondence course in Simple Linear Regression and Correlation Analysis and we've been arguing about the relationship between the correlation rxy and standard estimate of errorSy.x. I took statistics last year in high school and I remember something about the Sy.x being proportionate to the r. Are they inversely related, directly related, not related, or can only range from 0 to 1.00? Her book doesn't say very much and I believe they are inversely related. She says they're directly related. Answered by Chris Fisher and Penny Nom. 





An order relation 
20010212 

From Amy: What is an order relation? Answered by Claude Tardif. 





Body part measurements 
19991110 

From V Bailey: I am a kindergarten teacher and mother of a 6th grader who wants to do a science project on the correlations of body part measurements. We heard this on the radio and it sparked our interest, but now I cannot find any information about it. Examples are: your height is supposed to equal the distance from fingertip to fingertip when your arms are outstretched. Your foot size is supposed to equal the distance from your wrist to your elbow. Please help me find more information on this topic. Answered by Penny Nom. 





Equivalence Relations 
19990506 

From Megan: I am tutoring a boy who got this assignment from his teacher and I have no clue how to do it because I don't even know what the questions is asking! I need some help. Hereit is: "Give five examples of relations which are not equivalent relations and five examples of equivalent relations and explain why they are equivalent relations." This is seventh grade and I read about it in his book but it is not coming together for me. Answered by Chris Fisher. 





Pay Phone Problem 
19980226 

From Shameq: Hi, I've been given a problem that I'm having some trouble with. I'd really appreciate any help. Here's the question (it's called the Pay Phone Problem) A pay phone will take only 10p, 20p, 50p, and £1 coins"(It's British). A woman has plenty of 10p and 20p coins. She has no other coins. She can put the coins into the pay phone in any order. INVESTIGATE the number of different ways, she could put the 10p and 20p coins into the pay phone. Answered by Penny Nom. 

