CentsLord

(Eu tive que traduzir minha resposta do inglês para o português, mas espero que seja entendido!)

Portanto, a temperatura inicial é de -7 graus Celsius. Agora, subtraímos 18 deste número.

-7 - 18 = - (7 + 18), que é -25. Você pode solicitar a ajuda de uma linha numérica para ver como isso funciona.

Então, a temperatura de Moscou após a queda repentina de temperatura foi de -25 graus Celsius! :D

Nice, you're getting into set theory! I am not the best at this stuff, but I'll try :D

For teh first one:

Whenever we see an apostrophe next to the set, it means to take the complement of that set. This means, it includes all the things that ARE NOT n that set. For this one, it says X', which means everything that is not in X. So it would be C :D

For teh second one:

a)

(i) So you see that "U" symbol? That "U" stands for Union: Everything that is in A or B. This also includes everything in A and B, so basically just A + B. Here, it would be everything in the circles - 8, 14, 17, 16, 9 and 12.

(ii) This "n" symbol is kind of the opposite, but not really - it stands for an Intersection. This one is fairly obvious to understand - it is everything which is in the intersection of A and B :)

Here, it would be 14 and 17 :D

b) I'm not sure what that "/" symbol is on top of the A, but I'm assuming the question-makers tried to make an apostrophe (a complement). I trust that you can now solve this one on your own! :D

I'll just assume you need help on BOTH the problems :D

For (7)

This is a problem of ratios. The ratio of an object's height to its shadow length will be the same at the same time.

The ratio between the person's height and their shadow length is 6 : 10, or 3 : 5.

Let's say the tower's height is T. 

We know that:

T : 400 ft (Shadow length) = 3 : 5

This also means that T/400 = 3/5

We can cross-multiply to get 5T = 1200

Now we can simply divide to get T = 1200 / 5 = 240 ft, which is the 4th option :D

For (8)

Another problem on ratios :) Here the ratio between the height and the width of the photograph is being considered.

The ratio between the height and width is 4 : 6, or 2 : 3.

Let's say the future height of the photograph is H. 

We know that:

H : 10 = 2 : 3

This also means that H/10 = 2/3

Now we can cross-multiply to get 3H = 20

Then we can divide to get H = 20/3 = 6.666 in. forever! (rounded to 6.7, which is the 4th option agan!) :D

So Leo reads 11 pages in half an hour, which is 30 min.

There are 60 min in one hour, so he would read double the pages.

11 * 2 = 22, so Leo reads 22 pages per hour. That is his unit rate :D

Hours per page? Well, just divide by 22 to get 1 page per 1/22 hours, which basically means 1/22 hours per page. :D

There's a 1/2 chance the tiles will differ in material (wood or plastic).

There's a 1/3 chance the tiles will differ in color (r, y or b)

There's a 1/4 chanec the tiles will differ in shape (t, s, p or c)

So, there' s a 1/2  *  1/3  *  1/4 = 1/24 chance the two tiles will differ in respects to all the 3 properties! :D

Intriguing question. 

So, on the 0th day, there are 3 cells.

On the 2nd day, there are 6 cells.

On the 4th day, there are 12 cells.

On the 6th day, there are 24 cells.

On the 8th day, there are 48 cells :D

So, problem 2 (forgot to do this one)

The box represents everyone (80 people total).

The people ONLY in the box and NOT in any of the circles are people who don't study French or Spanish. Inferior souls (Just Kidding :D)

And there are 80 - 71 = 9 of those people.

14 people study ONLY Spanish (not answer to c), and 25 people study ONLY French (is the answer to b)

In the middle (the intersection), there are 71 - (14 + 25) = 71 - 39 = 32 people who study both French and Spanish.

Now, we know there are 32 + 25 = 57 people studying Spanish (not only spanish).

:D

I like these kinds of questions

So, there's 7 where B, C, and P intersect (the middle).

If there's 12 people in B and C, and 7 of those are already in the BCP, then there's 12 - 7 = 5 people in B and C ONLY (The middle-top intersection), not P

If there's 15 people in B and P, and 7 of those are already in the BCP, then there's 15 - 7 = 8 people in B and P ONLY (The middle-left intersection), not C

If there's 20 people in C and P, and 7 of those are already in the BCP, then there's 20 - 7 = 13 people in C and P ONLY (The middle-right intersection), not C 

If there's 35 people in the entire circle of B, and (7 + 5 + 8) = 20 are already in other regions too, then there's 35 - 20 = 15 people in B ONLY (The left huge area)

If there's 32 people in the entire circle of P, and (7 + 8 + 13) = 28 are already in other regions too, then there's 32 - 28 = only 4 people in P ONLY (The bottom huge area)

Now, for the remainder of C, we just add up the values we've already put in the venn diagram, and subtract that sum from the total number of students (60).

That sum is 7 + 5 + 8 + 13 + 15 + 4 = 52

60 - 52 = 8

Therefore, there are 8 people in C ONLY (The right huge area).

Hope you followed along :D

EDIT - forgot to do the other problem :( will make another answer

if you're taking geno3141's advice -

If you're in elementary school, 3-4 sentences for each paragraph should be about right. Middle school, then make that 5-6 sentences, complete with extravagant word choice!

For question 1040 (pupils):
 

It is fairly obvious that the "walk" portion of the pie chart is 1/4 of the entire thing, and the right angle confirms that.

As 1/4 of 36 (the total) is 9, there are 9 pupils walking to school.

The "Bus" portion is 120 degrees. We know that the total number of degrees in a circle is 360, and the total number of kids in the "Bus" portion will be 120/360 * 36 (the total), which is 12. So, 12 pupils take the bus.

Now for the "Bike" and "car". We know that the total number of degrees in a circle is 360. 90 + 120 = 210 degrees have already been taken by the "walk" and "bus" pupils, so the degrees of the "Bike" and "Car" portions should add up to 360 - 210 = 150 degrees.

The total pupils in the "Bike" and "Car" portions should add up to 15 pupils.

"Bike" and "Car" cannot have the same number of pupils - otherwise there would be 7.5 pupils in each! It looks like to me that the "Car" part is slightly larger than the "Bike" pupils, so 8 pupils in cars and 7 pupils in bikes seems like a safe bet. I'm assuming you need a protractor for these problems - It's pretty hard for me to give an answer backed by hard evidence, but I tried my best. If you use a protractor, you should get a reliable answer! :D

For question 1041 (villagers)

Let's assume the "Over 60" portion is half, because it seems to me the question would be impossible if we just had to guess. Again, protractor :o But then the "Over 60" portion would be half of 120, which is 60 villagers over 60 (ironic, because 60 is NOT over 60 :D ).

Okay, now I REALLY think this problem needs a protractor, because this is impossible without one. How do we know how many degrees "Under 25" is? Try it with one and see what you get :)