[Jonas Reitz]

If you are confused about something on the review sheet for Exam 1 (which will be handed out at the field trip today), post it here. If can answer a question, please do so!

[edaocello]

4c.) To find the perimeter (circumference) of the circle you may use two equations to solve it. you can either do
C=2(3.14)r
OR
C=(3.14)d.

but for either which one i used, I got the answer: 37.68 and not the answer on the sheet:18.84

I used
C=2(3.14)6= 37.68
AND
C=(3.14)12= 37.68

Is there something I’m doing wrong? I’m not sure how to arrive to the answer that was written on the answer sheet.

[kgardiner17]

I have a question about #`s 9b and 10…

[edaocello]

for number 10 i set up a proportion. I did cups of butter of sups of sugar. So for the first side it was 2 cups butter and 3 cups sugar. the second side it was 5 cups sugar so your proportion should look like this:

2 x
— = —
3 5

(the “x” is because you dont know how many cups of butter you need for that 5 cups of sugar)
and from there you cross multiply and end up with:

3x=5×2
3x=10
(then you want x on its own, so you would dived by 3 on both sides causing it to equal:)

x=3.333333333

the 3 before the decimal shows that you need 3 cups but arent sure what the decimal is as a fraction so you would subtract the 3 (cups) from your above decimal and if on the calculator, then you would press the button that turns decimals in fractions and it would equal 1/3

so you would need 3 1/3 cups of butter

[Jonas Reitz]

@edaocello, you are correct on both counts — these are errors in the answer key, which will be fixed shortly.
CORRECTIONS TO ANSWER KEY:
4c) the circumference should be 37.68 miles.
10) the answer is 3 and 1/3 cups of butter (or 10/3 cups butter, or 3.33333 cups butter)
Good work!

[Jonas Reitz]

@kgardiner17, I’d be happy to help, but could you explain a little more about what your question is?

[edaocello]

thank you for your reply and making sense of it for me! everything else is pretty clear to me except for number 13. I do not have a clue where to begin to arrive to the answer at all. may you help me please?

[Jonas Reitz]

@edaocello, in number 13 you should start by drawing a picture. HINT: make a triangle — one side is the building, one side is the ground, and the hypotenuse goes from the tip of the building to you (the viewer on the ground). What sides and angles do you know? Hope this helps – let me know if you’re still stuck!

[edaocello]

Yes it did help thank you! I ended up with 1,455 ft and the answer on the answer sheet was 1,454 feet but i figured that its still right, correct?

[Jonas Reitz]

@edaocello, I’m guessing the difference has to do with rounding off error — it depends on how many digits you take from the calculator when computing the trig functions. It might be worth trying again (using more digits — for example, 4 or 5) to make sure your answer agrees with the answer key, but this is not a serious error.

[brina92]

Where do you find the answers to the review sheet on open lab?

[Jonas Reitz]

@brina92, On the course website (click the link “Site” on the right side of this page to get there), you will see a menu item called “Exam Reviews” just underneath the main bridge picture. This has a link to the review sheet plus answer key — the answer key is the third page of the document. Here is a direct link: http://openlab.citytech.cuny.edu/mat1175fa2011/files/2011/09/2011FallMAT1175-Exam1Review.pdf
Let us know if this still gives you trouble.

[Shawn Luchiono]

Rahshawn Barber

Thanks A lot for the direct link!!

[john8ramroop]

Having some trouble with (9.b)
Dont really have an idea where to start.

[Jonas Reitz]

@john8ramroop, once you complete 9a (showing the triangles are similar), you can create a proportion relating the sides of the two triangles. The ratio of sides in the smaller triangle will equal the ratio of corresponding sides in the large triangle. It might help to look at the notes from Day 3: http://openlab.citytech.cuny.edu/mat1175fa2011/day-3-%E2%80%93-proportions-similar-triangles/ . Write back if you’re still having trouble!