This Blog exists for the collective benefit of all 7th grade math students. While the posts are specific to Mr. Chamberlain's class, we welcome comments from everyone. The more specific your question (including your own attempts to answer it) the better.
EVEN MORE WELCOME ARE ANSWERS FROM FELLOW STUDENTS. BLOG ON!
In both #6 & #9, you are asked to find BOTH height AND diameter. So, for each problem you will have to set up TWO proportions, i.e. a proportion to find the height and a SECOND proportion to find the diameter... you can't do them both in one proportion.
I know you have to set up two proportions, but the answer doesn't look right. I did: 1in/2.5ft = 75ft/xin and 1in/2.5ft = 15ft/xin I then use the cross product property and the answer comes out to be 187.5 and 37.5
I absolutely LOVE LOVE LOVE that Maggie was able to tell me that her answer didn't look right... As I have promised, I will give partial credit for a wrong answer on a test, if you can tell me that your answer doesn't make sense.
As we have discussed many times in class, recognizing that you have made a mistake can sometimes be just as good as being right.
Ir a real life situation, Maggie would have been saying "Hey, before we go out and buy all of the material to build the silo, let's double-check my math"... and it would have been the "right thing to do."
#2 refers to a map that has a scale of 1"=75 miles. It simply asks how far does 2" represent?
The simple answer is to simply multiply 75 by 2 and you get your answer.
As we discussed in class, this "simple" math is fine to answer the question, but you are being asked at the same time to upgrade your view of such problems (as well as your vocabulary) and recognize that at the HEART of such problems is a proportional relationship... in this case:
1" is to 75 miles as 2" inches is to x miles
written in equation form, it looks like this: 1/75 = 2/x
Use the cross-product property (cross-multiplication) to solve this equation... I'll let you do that!
For #27, the ratio of 1 inch to 1/3 inch reduces to 3 to 1, so it is asking you to make an enlarged copy of the drawing. Re-read pg 192 about the oversized heart model for another example.
Dear #3, re-read the definition of scale on page 192 and let me know if you can answer the question for yourself.
The model of the heart is larger than an actual heart, so the first number is larger than the second. Typically when we think of a model, we think of an object that is smaller than the actual object, like a model car or airplane.
Many model cars are built using a 1/64 scale, meaning the model is 1/64 the size of the original. If a car model were build to a 1/32 scale, it would be 1/32 the size of an actual car, but twice as large as a 1/64 model.
that's what you are being asked to figure out... the question is asking you to draw the scale model... the actual figure is in the book... sleep on it and debate it with a friend tomorrow. You should be able to use the information in my previous comment to help you.
If that's the only question you are stuck on, you have done VERY WELL.
When working out, the expression is "no pain no gain"... Confusion is pain for the brain... Confusion is good!!
I can't get the answer to #6 & 9 on pg 194. I set it up as a proportion, but I can't seem to figure it out.
ReplyDelete-Maggie
In both #6 & #9, you are asked to find BOTH height AND diameter. So, for each problem you will have to set up TWO proportions, i.e. a proportion to find the height and a SECOND proportion to find the diameter... you can't do them both in one proportion.
ReplyDeleteDoes that answer your question??
I know you have to set up two proportions, but the answer doesn't look right.
ReplyDeleteI did: 1in/2.5ft = 75ft/xin and
1in/2.5ft = 15ft/xin
I then use the cross product property and the answer comes out to be 187.5 and 37.5
ahah, ok, you described your issue well!
ReplyDeleteWhen you set up a proportion, you MUST compare CORRESPONDING parts in the proper order, i.e. you need to "say":
"like is to like, as like is to like"
... what the heck am I talking about?!
for example, in this problem, you could say:
"the diameter of the model is to the diameter of the silo, as the height of the model is to the height of the silo"...
(i'll let you write the proportion)
you could have also said:
"the diameter of the model is to the height of the model, as the diameter of the silo is to the height of the silo"
(i'll let you write the proportion)
You should see that either proportion produces the identical cross products.
What you tried to say originally was:
"the diameter of the model is to the diameter of the silo, as the height of the silo is to the height of the model"...
... do you see the error of your ways, in essence, you "crossed up" your cross products... i.e. your "right-side" was upside-down.
Ca-peesh?
1in/2.5ft = 75ft/xin and
Oh, and a second thought for EVERYONE...
ReplyDeleteI absolutely LOVE LOVE LOVE that Maggie was able to tell me that her answer didn't look right... As I have promised, I will give partial credit for a wrong answer on a test, if you can tell me that your answer doesn't make sense.
As we have discussed many times in class, recognizing that you have made a mistake can sometimes be just as good as being right.
Ir a real life situation, Maggie would have been saying "Hey, before we go out and buy all of the material to build the silo, let's double-check my math"... and it would have been the "right thing to do."
i dont get 2 and 27
ReplyDeletefor number 3, which way do the scales go?
ReplyDeleteI don't get 6 and 9 either. I had the same problem as Maggie. Your explanation confused me even more.
ReplyDeleteWell, gosh, at least I tried. We'll go over the problems in class... have you tried the video tutors?
ReplyDeleteIf you can articulate your vision of the problem, I can still try to help (I'm not easily discouraged!)
Dear #2 and #27,
ReplyDelete#2 refers to a map that has a scale of 1"=75 miles. It simply asks how far does 2" represent?
The simple answer is to simply multiply 75 by 2 and you get your answer.
As we discussed in class, this "simple" math is fine to answer the question, but you are being asked at the same time to upgrade your view of such problems (as well as your vocabulary) and recognize that at the HEART of such problems is a proportional relationship... in this case:
1" is to 75 miles as 2" inches is to x miles
written in equation form, it looks like this:
1/75 = 2/x
Use the cross-product property (cross-multiplication) to solve this equation... I'll let you do that!
Ca-peesh?
For #27, the ratio of 1 inch to 1/3 inch reduces to 3 to 1, so it is asking you to make an enlarged copy of the drawing. Re-read pg 192 about the oversized heart model for another example.
ReplyDeleteDear #3, re-read the definition of scale on page 192 and let me know if you can answer the question for yourself.
ReplyDeleteThe model of the heart is larger than an actual heart, so the first number is larger than the second. Typically when we think of a model, we think of an object that is smaller than the actual object, like a model car or airplane.
Many model cars are built using a 1/64 scale, meaning the model is 1/64 the size of the original. If a car model were build to a 1/32 scale, it would be 1/32 the size of an actual car, but twice as large as a 1/64 model.
Ca-peesh?
num 27 is the drawing supposed to be larger or smaller?
ReplyDeletethat's what you are being asked to figure out... the question is asking you to draw the scale model... the actual figure is in the book... sleep on it and debate it with a friend tomorrow. You should be able to use the information in my previous comment to help you.
ReplyDeleteIf that's the only question you are stuck on, you have done VERY WELL.
When working out, the expression is "no pain no gain"... Confusion is pain for the brain... Confusion is good!!
We'll debate it in class on Weds!
I got the answers for #6&9, thanks Mr. Chamberlain. Your the best!
ReplyDelete-Maggie