hw#4-4: Due Monday Dec 19th
pg 252 #1-11 All
pg 282-283 #6-12 Even
pg 257 #9-14 All
It would be really really NICE if you guys spread the word to each other...
UPDATE: UNIT TEST on section 4-1 thru 4-5 (OMIT 4-6 & 4-7) Wednesday, Dec 21st
You should have a clear understanding of the concrete tube (pg 251#19) and the level of detail that I expect you to provide. Any other questions??
This has been ONE CRAZY UNIT so far... how are you doing? You can ask questions on this post for ANYTHING from 4-1 thru 4-4... chat at'cha later!... USE THE GRAPHING CALCULATOR to check your work... Mr. C.
Being honest...I do not completely understand the tube could i come in early or afterschool before the test i just need a reniforcement because I felt like everyone was getting it but me... And i worry that if im faced with a problem like on the test that ill definitely get it wrong...
ReplyDeleteTrust me, if you're not sure about it, neither is about 1/2 the class. We will be working on word problems (story problems) all class on Monday.
ReplyDeleteI will be available at 7:15 each day this week AND I will be available after school on Monday til 4pm and Tues til 3:15pm.
I will not be available for questions tomorrow (Sunday), but I will try to do a couple of videos, if possible.
For the concrete cylinder/tube and bags of concrete problem... and may I suggest you "play along" with a pencil and paper?...
ReplyDeleteThe formula for the volume (the amount of "liquid" concrete that would be poured into the tube) is:
V=πr^2h
... where h is the length of the tube... I'm using h instead of the letter L because a lower case L could look like a one, ok?
So, if the problem asked us for how much concrete we need, we would simply use that formula.
But the problem goes one step further. In real-life, you would read the directions on the bag of powdered concrete mix... in this case the bag says that if you mix the powdered concrete with water, it will make 2/3 cubic foot of concrete. This is not unlike looking at the directions for making iced tea from a powdered mix, get it?
So, how ever many cubic feet of concrete you need for doing anything (like filling a 4ft tube with a radius of 4inches) you would have to divide that amount of by 2/3 to see how many bags of powdered concrete mix you need.
Since you are a supreme algebra-tician, you know that when you divide by a number, you could equivalently multiply by its (all together now!) RECIPROCAL.
SO, since the formula to obtain the amount of concrete is πr^2h, we simply have to divide that by 2/3 and, voila, we have our new formula for the number of bags required.
In our infinite wisdom, instead of dividing by 2/3, we realize it would be a lot prettier if we multiplied by 3/2 (it pays to me so smart) and we thus obtain the pretty formula:
n=(3/2)πr^2h
where n is the number of bags of powdered concrete.
I hope you were taking notes!
Goodnight!
P.S. Ask your Q-buddy JF, she was all over this problem last year!
Thanks after we went over it in class, and your explanation here its clicking. I was definitely more confuzzled by the words than the actual problem. You really need to pick it apart
ReplyDeleteHi evan
ReplyDeleteWhat time should we come in for the review tommorrow morning?
ReplyDelete7:15
ReplyDelete