I need help with some word problems for Algebra II

[Borrowedhalo]

These are related to Linear Relations and Functions--

1. The equation y = 2.5x gives the length y in centimeters corresponding to a length x in inches. What is the length in centimeters of a 1-foot ruler?

2. For Meg's long-distance calling plan, the monthly cost C in dollars is given by the linear function C(t) = 6 + 0.05t, where t is the number of minutes talked. What is the total cost of talking 8 hours? of talking 20 hours? What is the effective cost per minute (the total cost divided by the number of minutes talked) of talking 8 hours? of talking 20 hours?

I have some for rate of change as well, but I will try to figure those out before I put them out there.

Thanks.

 

[Deleted member 4993]

These are related to Linear Relations and Functions--

1. The equation y = 2.5x gives the length y in centimeters corresponding to a length x in inches. What is the length in centimeters of a 1-foot ruler?

How many inches in 1-foot?

Then,

What is the value of 'x'?

2. For Meg's long-distance calling plan, the monthly cost C in dollars is given by the linear function C(t) = 6 + 0.05t, where t is the number of minutes talked. What is the total cost of talking 8 hours? of talking 20 hours? What is the effective cost per minute (the total cost divided by the number of minutes talked) of talking 8 hours? of talking 20 hours?

How many minutes in 1 hour?

How many minutes in 8 hours? What is the value of 't' for this case?

How many minutes in 20 hours? What is the value of 't' for this case?

I have some for rate of change as well, but I will try to figure those out before I put them out there.

Thanks.

Please read the post titled "Read before Posting".

We can help - we only help after you have shown your work - or ask a specific question (not a statement like "Don't know any of these")

Please share your work with us indicating exactly where you are stuck - so that we may know where to begin to help you.

 

[Borrowedhalo]

I'm sorry, I'm still stuck...

Ok, let's start with the first one. I get that there are 12 inches in a foot, but I don't see where that helps me. Bear with me, I'm 40 and I haven't done this in a long time. I'm trying to get it so that I can explain it to my 16 year old! I know I'm right before the light-bulb!

Do I set x at 12?

1. The equation y = 2.5x gives the length y in centimeters corresponding to a length x in inches. What is the length in centimeters of a 1-foot ruler?

How many inches in 1-foot?

Then,

What is the value of 'x'?

Ok, yeah...got it.

Now the next one.....

 

[Borrowedhalo]

Next one...

2. For Meg's long-distance calling plan, the monthly cost C in dollars is given by the linear function C(t) = 6 + 0.05t, where t is the number of minutes talked. What is the total cost of talking 8 hours? of talking 20 hours? What is the effective cost per minute (the total cost divided by the number of minutes talked) of talking 8 hours? of talking 20 hours?

How many minutes in 1 hour?

How many minutes in 8 hours? What is the value of 't' for this case?

How many minutes in 20 hours? What is the value of 't' for this case?

Ok, so I take C(t) = 6 + 0.05 (60) --> one hour? (480) --> 8 hours, etc.?

Then I can figure cost per minute.

 

[Borrowedhalo]

Rate of Change

Ok, these seem too obvious...

Washer costs $15,600 new...worth $7,500 after 3 years...worth $2800 after 8 yrs.

Find the average rate of change in value of the machine between its purchase and the end of 3 years.

Wouldn't that just be the difference divided by 3 to give me an average?

Then:

Find the average rate of change in value of the machine between the end of 3 yrs and the end of 8 years.

Wouldn't that be the same thing divided by 5 (the difference between 8 and 3)?

And last:

Interpret the sign of your answers.

Pretty sure we're not talking about astrology all of a sudden! No idea what this is asking for!

 

[Deleted member 4993]

Ok, these seem too obvious...

Washer costs $15,600 new...worth $7,500 after 3 years...worth $2800 after 8 yrs.

Find the average rate of change in value of the machine between its purchase and the end of 3 years.

Wouldn't that just be the difference divided by 3 to give me an average?

Yes..

average rate of change = (7500 - 15600)/3 = -$2700/yr

The negative sign indicates that the price "decreased" over the years.



Then:

Find the average rate of change in value of the machine between the end of 3 yrs and the end of 8 years.

Wouldn't that be the same thing divided by 5 (the difference between 8 and 3)?

And last:

Interpret the sign of your answers.

Pretty sure we're not talking about astrology all of a sudden! No idea what this is asking for!

No astrology - the answer should conclude whether the average change indicates a decrease or increase in price.

.

 

[Borrowedhalo]

Thank you so much

Just wanted to say thank you. Your instructions were very clear, now I can go explain them to my son....right after I go pick up my OTHER son from hockey practice!!! Have a great night!