# Tutor.com Linear Equations Session

##### Jan. 17, 2013

Session Transcript - Math - Algebra, 12/11/2012 3:34PM - Tutor.comSession Date: 12/11/2012 3:34PM
Length: 25.1 minute(s)
Subject: Math - Algebra

System Message
[00:00:00] *** Please note: All sessions are recorded for quality control. ***

Harmony (Customer)
[00:00:00] A company finds it has a cost of \$33,290 with a production level of 1200 and a cost of \$97,510 when they produce 3800 items. Find the linear cost and identify the fixed cost and the variable cost per item.

Alvaro O (Tutor)
[00:00:13] Welcome to Tutor.com ! Let's get started.

Harmony (Customer)
[00:00:35] k, sounds great

Alvaro O (Tutor)
[00:00:58] Have you started working on the problem?

Harmony (Customer)
[00:01:14] No, I'm pretty lost with where I need to start

Alvaro O (Tutor)
[00:01:30] No worries, I'd be glad to lead you in the right direction

Harmony (Customer)
[00:01:36] Thank you

Alvaro O (Tutor)
[00:01:44] No problem!
[00:02:05] So we are given two costs with their respective production levels
[00:03:29] We can think of these as x,y points

Harmony (Customer)
[00:03:46] k

Alvaro O (Tutor)
[00:03:55] Where the x's are the production and y is the cost
[00:05:07] With this in mind, the question asks for the fixed cost and the variable cost
[00:05:56] So if we were to represent this as a line y = mx + b, which is the fixed cost and which is the variable cost?

Harmony (Customer)
[00:06:49] slope ? m=y2-y1/x2-x1?

Alvaro O (Tutor)
[00:07:06] Right! Slope is one of them.
[00:07:15] That would be our variable cost
[00:07:32] So our fixed cost would be b
[00:08:29] So lets first use that equation to solve for m

Harmony (Customer)
[00:11:18] 24.7

Alvaro O (Tutor)
[00:11:26] Excellent!
[00:12:01] Now we need to solve for b

Harmony (Customer)
[00:13:06] can I use either of the (x,y)? like (1200,33290)

Alvaro O (Tutor)
[00:13:29] Right! Either one would be correct

Harmony (Customer)
[00:14:27] umm i'm not sure how to write it
[00:14:41] 33290=24.7x

Alvaro O (Tutor)
[00:15:06] Thats right! Just missing a small detail...
[00:15:45] So we need to plug in our x value and solve for b

Harmony (Customer)
[00:16:08] 33290=24.7(1200)=

Alvaro O (Tutor)
[00:18:00] I'm working on this...
[00:18:49] Did you get an answer?

Harmony (Customer)
[00:19:13] no i'm getting a super long number

Alvaro O (Tutor)
[00:20:15] Alright, well lets work through it together to see what we get

Harmony (Customer)
[00:20:25] k

Alvaro O (Tutor)
[00:20:40] Thats right so far! Now we should multiply
[00:20:46] 24.7 and 1200

Harmony (Customer)
[00:21:02] 29640

Alvaro O (Tutor)
[00:21:07] Great!
[00:21:13] And one last step...

Harmony (Customer)
[00:21:28] subtract 33290
[00:21:45] 3650

Alvaro O (Tutor)
[00:21:52] Great!
[00:22:00] So that is our b value

Harmony (Customer)
[00:22:08] k
[00:22:18] that was easier than I thought lol

Alvaro O (Tutor)
[00:22:36] Thats alright, the problem was worded in a tricky way
[00:22:41] So what is our resulting line?
[00:22:57] line equation*

Harmony (Customer)
[00:23:02] Cx=24.7x+3650

Alvaro O (Tutor)
[00:23:13] Excellent!
[00:23:27] Any questions about what we did?

Harmony (Customer)
[00:23:39] nope I understand that

Alvaro O (Tutor)
[00:24:05] I'm glad to hear it! Well it was a pleasure working with you.

Harmony (Customer)
[00:24:11] Thank you!!
[00:24:16] I appreciate it!

Alvaro O (Tutor)
[00:24:19] Keep up the great work.
[00:24:32] You're welcome
[00:24:45] Have a great day and please rate me in the survey!