Both companies charge the same amount when the total duration of monthly calls is

eddy2017

eddy2017

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hi, need a hint that starts me off on this
Two companies offer monthly cell phone plans, both of which include free text messaging. Company A charges a $25 monthly fee plus five cents per minute of phone conversation, while Company B charges a $50 monthly fee and offers unlimited calling. Both companies charge the same amount when the total duration of monthly calls is

8 hours and 33 minutes

5 hours

500 hours
8 hours and 20 minutes

someone told me you got two straight lines, one horizontal and the other with a slope of 0.05 (five cents).
why?, how do i know they are straight lines?. i'm not getting it.
any hints?
thanks,
eddy
 
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eddy2017 said:
hi, need a hint that starts me off on this
Two companies offer monthly cell phone plans, both of which include free text messaging. Company A charges a $25 monthly fee plus five cents per minute of phone conversation, while Company B charges a $50 monthly fee and offers unlimited calling. Both companies charge the same amount when the total duration of monthly calls is

8 hours and 33 minutes

5 hours

500 hours
8 hours and 20 minutes

someone told me you got two straight lines, one horizontal and the other with a slope of 0.05 (five cents).
why?, how do i know they are straight lines?. i'm not getting it.
any hints?
thanks,
eddy
Click to expand...
Draw a coordinate plane. X axis is the total duration of monthly calls (x min). Y axis is the monthly charge.
Company A charge is expressed by what function of x? And company B?
Can you graph these 2 functions?
What point represents the charge A being equal to charge B?
 
thanks, lev. the question was already answered but i was in doubt about how a friend of mine knew that these two lines were straight. he is a good at math and he just looked at the problem and told me you have two straight lines there. i kept on thinking about it. had to ask you how he knew that. thanks i will try to do what you asked me to and if i get stuck ill let you know.
give me sometime pls
 
eddy2017 said:
thanks, lev. the question was already answered but i was in doubt about how a friend of mine knew that these two lines were straight. he is a good at math and he just looked at the problem and told me you have two straight lines there. i kept on thinking about it. had to ask you how he knew that. thanks i will try to do what you asked me to and if i get stuck ill let you know.
give me sometime pls
Click to expand...
Your friend looked at the relationship between the duration and the total charge and concluded that it is linear, i.e. of type y = mx + b.
 
lev888 said:
Your friend looked at the relationship between the duration and the total charge and concluded that it is linear, i.e. of type y = mx + b.
Click to expand...
Oh that is it!.
Okay but I'll try and graph them and send it. I need to learn to do that
 
lev888 said:
Draw a coordinate plane. X axis is the total duration of monthly calls (x min). Y axis is the monthly charge.
Company A charge is expressed by what function of x? And company B?
Can you graph these 2 functions?
What point represents the charge A being equal to charge B?
Click to expand...
Thanks for the hint. If you know of an online took to graph equations and can send the link it'll be good. Tx
 
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Frankly, I don't see any reason to draw a graph. You are told that one company charges $25 monthly fee plus $5 per minute, so if there are m minutes of calls the charge will be 25+ 5m, while the other charges a $50 flat fee. The charges will be the same when 25+ 5m= 50. Solve that for m.
 
HallsofIvy said:
Frankly, I don't see any reason to draw a graph. You are told that one company charges $25 monthly fee plus $5 per minute, so if there are m minutes of calls the charge will be 25+ 5m, while the other charges a $50 flat fee. The charges will be the same when 25+ 5m= 50. Solve that for m.
Click to expand...
25+0.05m=50
25-25+0.05m=50-25
m=500
both companies charge the same amount when the total duration of monthly calls is 500 hours
 
Last edited:
lev888 said:
Draw a coordinate plane. X axis is the total duration of monthly calls (x min). Y axis is the monthly charge.
Company A charge is expressed by what function of x? And company B?
Can you graph these 2 functions?
What point represents the charge A being equal to charge B?
Click to expand...
i can graph them just i need to know this
this equation y=25+0.05x,
can i use the the y=mx+b formula here, does the equation follow the order of the formula, or the order is not important.
i mean by order that the constant (y-intercept) comes before and the mx after it, does it matter?
 
Huh- I really screwed that up! The charge by the first company was $25 plus 5 cents per minute, not 5 dollars per minute nor 5 dollars per hour! The charge for m minutes is 25+ 0.05m= 50. 0.05m= 25. m= 25/0.05= 500 hours!

That is NOT the "average duration" of calls, it is the total duration of monthly calls.
 
HallsofIvy said:
Huh- I really screwed that up! The charge by the first company was $25 plus 5 cents per minute, not 5 dollars per minute nor 5 dollars per hour! The charge for m minutes is 25+ 0.05m= 50. 0.05m= 25. m= 25/0.05= 500 hours!

That is NOT the "average duration" of calls, it is the total duration of monthly calls.
Click to expand...
lol, my prandpa used to say 'even the best of scribes make a spelling mistake once in a while'. lol, thanks a lot
i wanna graph them for practice.
my question to lev was:
y = 25 + 0.05 x
is this equation in slope intercept form even when the mx is at the end?.
 
eddy2017 said:
lol, my prandpa used to say 'even the best of scribes make a spelling mistake once in a while'. lol, thanks a lot
i wanna graph them for practice.
my question to lev was:
y = 25 + 0.05 x
is this equation in slope intercept form even when the mx is at the end?.
Click to expand...
The order in which you add things is irrelevant

3 + 7 = 7 + 3

mx + b = b + mx.

People would find algebra a lot easier to grasp if they would keep in mind that each letter just represents a number.
 
JeffM said:
The order in which you add things is irrelevant

3 + 7 = 7 + 3

mx + b = b + mx.

People would find algebra a lot easier to grasp if they woild keep in mind that each letter just represents a number.
Click to expand...
Thanks a lot, Jeff!
 
lev888 said:
Draw a coordinate plane. X axis is the total duration of monthly calls (x min). Y axis is the monthly charge.
Company A charge is expressed by what function of x? And company B?
Can you graph these 2 functions?
What point represents the charge A being equal to charge B?
Click to expand...
charge A = to charge B at point 0.
please confirm
i am having doubts about how to graph this
i know that
company 1: y = 25 + 0.05 x

company 2: y = 50

what does lev mean by this?
Company A charge is expressed by what function of x? And company B?
??????>
 
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eddy2017 said:
charge A = to charge B at point 0.
please confirm
i am having doubts about how to graph this
i know that
company 1: y = 25 + 0.05 x

company 2: y = 50

what does lev mean by this?
Company A charge is expressed by what function of x? And company B?
??????>
Click to expand...
You answered my question by showing the 2 functions. I don't remember if you studied functions, but "y = blah blah x" is a function of x. y = 50 is also a function, since x is not present in the expression, the function is constant.
 
lev888 said:
Draw a coordinate plane. X axis is the total duration of monthly calls (x min). Y axis is the monthly charge.
Company A charge is expressed by what function of x? And company B?
Can you graph these 2 functions?
What point represents the charge A being equal to charge B?
Click to expand...
My doubt is about the graphing of the two functions. You want me to graph the two function that I gave you here?.
These ones?
y = 25 + 0.05 x
y = 50
Say yes or no.
 
lev888 said:
You answered my question by showing the 2 functions. I don't remember if you studied functions, but "y = blah blah x" is a function of x. y = 50 is also a function, since x is not present in the expression, the function is constant.
Click to expand...
Yes, I have studied functions and I'm studying lot of tutorials on the subject but sometimes I'm in doubt about what is required of me to do.
 
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