Question 1105216
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Could you please help with this math problem. I have to state the domain and range, the y-intercept, and say whether or not it's a function:
Jordon weighs 160 lbs. By lifting weights each month for a year, he continually gains weight until he is 200 lbs.<br>
The thing being watched is Jordon's weight as time goes by for a year.  We don't know whether his weight gain is linear; we only know it is 160 at the beginning of the year and 200 at the end.  So...<br>
domain: His weight is being monitored over the course of a year; however, it is not clear what the domain should be, because we don't know how often his weight if begin measured.  But the problem says he is "lifting weights each month for a year", which IMPLIES that "months" should be the unit in the x direction on the graph.  Since he is monitoring his weight for 1 year (12 months), the domain is [0,12].  Of course the domain will be different if he continues to monitor his weight after the one year.<br>
range: From his beginning weight to his ending weight -- [160,200].  Since the problem doesn't say he gains weight at a constant rate, we can't be sure that is the right answer.  At the beginning of the year, he might have dipped below 160 for some reason initially; and/or at the end of the year he might have gone a bit over 200.  So we can't be sure [160,200] is the actual range -- but it's the only answer we can give with the given information.<br>
y-intercept: His weight at the beginning, 160.<br>
function?: Yes; at any time during the year he only had one weight.<br>
You say you don't know what the equation would be; and in fact we don't know what it would be, because we don't know that his weight gain was at a constant rate (and in reality it is very unlikely that it was).<br>
Finally a note about how you show one of your answers....  The statement {{{160>=x<=200}}} does not say what you want it to.  You want it to say that x is greater than or equal to 160 and less than or equal to 200; but the way you write it says it is less than 160 and less than 200 -- which not only doesn't make sense, it is also wrong.  The correct way of writing that answer is {{{160<=x<= 200}}}.