Easy math assignment - 10k SAMP cash as reward. (updated 17:04)

[Seskom]

1)Sisters and brothers age together is 50 years. 10 years ago brother was twice as old as sister. How old are they now?

  You must explain how you reach to the answer.

Soloved by xcasio, next one is


2)two bikers (Bob and Mary) were racing on a 150km long track. Bob reached the finish 20 minutes before Mary and Bob's speed was 5km/h faster then Mary's speed. how many hours it took for Bob to pass the track?

Explain how you reach the outcome of your math.

3)You have an square looking metal plate. If you cut off 3 cm from the edge you will get an metal plate with area 10cm (squared) (s=10cm)
question: What were the measures of the plate in the beginning

Soloved by gimli.

Explain how you reach the outcome of your math.

[Dean Willis]

80?

[Seskom]

80?

How can you get 80 if x1+x2=50?

[Gimli]

x - brother, y - sister

x+y = 50
2x+x = 30 //10 years ago - take away 20 from the result
3x = 30

x = 20+10
y = 10+10

brother - 30, sister - 20

10 years ago the brother was 20 and the sister was 10

[Seskom]

x - brother, y - sister

x+y = 50
2x+x = 30 //10 years ago - take away 20 from the result
3x = 30

x = 20+10
y = 10+10

brother - 30, sister - 20

10 years ago the brother was 20 and the sister was 10

Correct, new math assignment added.

[Gimli]

Correct, new math assignment added.

Ohh I thought you needed this for something

[Seskom]

Ohh I thought you needed this for something

I do :P I'm gonna get grades for this shit just that I don't know how to solove these :P

I have soloved most of them myself but some are too hard for me.

[alamicu]

3)You have an square looking metal plate. If you cut off 3 cm from the edge you will get an metal plate with area 10cm (squared) (s=10cm)
question: What were the measures of the plate in the beginning

Explain how you reach the outcome of your math.

small square area = 10 cm so the side of the small square is SQRT(10) = 3.16. you cut 3cm from de edge so the big square side is 3.16+3(edge1)+3(edge2)=9.16. The area of the big square is SQR(12.16)=83.905... almost 84
 
i guess...wasn't that good at math )

edited )

[Seskom]

small square area = 10 cm so the side of the small square is SQRT(10) = 3.16. you cut 3cm from de edge so the big square side is 3.16+3(edge1)+3(edge2)=12.16. The area of the big square is SQR(12.16)=147.86
 
i guess...wasn't that good at math )

if you cut off 3cm from only one edge it wont be a square anymore 

[alamicu]

btw i`ve made a corection in my previous post
yeah but you could cut 4x3cm or 2x3cm...so the results aren`t the same
if you cut 4x3 cm then the result is in my previouse post
if you cut 2x3 cm then the result is SQR(3.16+3)=37.94... =38

[Seskom]

btw i`ve made a corection in my previous post
yeah but you could cut 4x3cm or 2x3cm...so the results aren`t the same
if you cut 4x3 cm then the result is in my previouse post
if you cut 2x3 cm then the result is SQR(3.16+3)=37.94... =38

I need to know the lenght of the square sides like

        x cm
      |-----|
x cm|       |xcm
      |       |
      |-----|
        x cm

[Steve.]

I am not so good at maths.
So I can't help you. 

[Seskom]

come on, I got to finish this in 2 hours.

[Norrage]

Or just do it yourself. Anyways ill try 3) for you.

Like lets say,
You have this square:

        A         10cm          B
        +------------------+
        |                          |
        |                          |
10cm |                          | 10cm
        |                          |
        |                          |
        |                          |
        +------------------+
       C          10cm          D

And you cut 3 cm of each edges, you need to know the size?
Or do you need to cut for example 3 cm off C-D?

[Seskom]

        A         x   cm        B  so this edge should be x-3 I think but I'm not sure.
        +------------------+               ONE of the edges has been cut from the original square shape.                     
        |                2        |
 x cm |        10cm           | x cm
        |                          |
        +------------------+
       C          x cm          D

So we have a square like this, we dont know the edges, we just know it looks like a square.
                                                                                                                                                                                           2
Then you cut 3cm off an edge, just one edge. You will get that the AREA inside the cut square (obviously isn't an square anymore) is 10 cm

SO you have that the shape wich edge has been cut 3cm has an area inside it 10cm2

Now you need to find the SQUARE's first edge lenght.



        A         x cm          B
        +------------------+
        |                          |
        |                2         |
x  cm |          x cm          |  x cm
        |                          |
        |                          |
        |                          |
        +------------------+
       C          x cm          D