[littlemissy]

I don't get how to do these problems... I would appreciate any help. Thanks.


1.) Annie drives from town A to town B in 3 hours (at a fixed speed). The traffic is heavier on the return trip, so Annie's speed is 20 mph less and the return trip takes 4 hours. What were her speeds on both parts of the trip?

2.) Is there a positive real number such that the sum of the number and its square is 1? If so, find the number.


3.) Is there a positive real number such that the difference between the number and its square is 1? If so, find the number.


4.) In a certain rectangle, the length exceeds the width by 2 m. If the length is increased by 4 m and the width is decreased by 2m, the area of the new rectangle is the same as that of the original rectangle. Find the dimensions of the original rectangle.


5.) You invest $900 in stock paying a 6% annual dividend and $300 in stock paying a 8% annual dividend. How many years will it take for the total earnings to equal the total initial investment? (Use the formula I = P r t.)


6.) How much water must be evaporated from 400 Ib of a 10% salt solution to yield a solution that is 18% salt?


7.) Annie drives from town A to town B in 3 hours (at a fixed speed). The traffic is heavier on the return trip, so Annie's speed is 20 mph less and the return trip takes 4 hours. What were her speeds on both parts of the trip?

[Melitus]

wtf...is this highschool math? cause it's drivin me insane. Umm i truly don't get any of those questions lol. sorry i'm one asian that failed poorly when it comes to math.

[BabyK]

What math class are you in? Pre-Algebra? Algebra? Geometry? Algebra 2?

I MIGHT be able to figure out the first one =.=;; It's like my Science homework.

[Saebin :D]

i'm sorry i cant help, my eyes turn like this when i see math problems :

plus these are hard.
or maybe it's just that im dumb.
oh well.

good luck


EDIT:
btw, i just read the first question.
shouldnt it be something like,

x mph + ( x mph - 20mph) ?

x being the speed on her way there.

[littlemissy]

I'm taking algebra right now. Thanks for the help.

[peachesapples123]

I remember word problems in math when I was in Algrebra...I sucked so much at them. Word problems was my weakness. And I didn't start getting Algebra in general until the end of the year. XP Sorry, I didn't say anything that could've helped you. 2-3 of those questions was totally similar to the word probems I had serious trouble with.

[tangerine_kisses]

goodness...the last time i had that was 2 years ago. ok so i'm going to try to help.
if i remember, i'll come back and edit this post.
but if my memory already went down the drain...sorry.

i used to love those kind of problems during freshman year.
your numbers 1 & 7 are the same problem

EDIT: i may not be able to answer all of the problems. sorry.
(don't trust me answers too much...i'm not a whiz at math. and sorry, i'm not good at explaining)

1. & 7. Let x=Annie's speed going to town B. x-20=her speed returning
since (speed)(time)=distance


EQUATION: 3x=4(x-20)
*they're equal because Annie took the same route to and from.

so 3x=4x-80
x=80
x-20=60

So the answer is: Annie's speed on her trip to town B is 80 mph and 60 mph on her way back.

3. OLD RECTANGLE: Let x=measure of width. x+2=length
NEW RECTANGLE: Let x-2=new width. x+6=new length

since AREA OF RECTANGLE=(LENGTH)(WIDTH)

EQUATION: x(x+2)=(x+6)(x-2)
x2 + 2x=x2+4x-12
*NOTE: x2 is x squared. i can't use superscript here in the forums
x2+4x-12 because you did FOIL method on (x+6)(x-2).
cancel x2.
2x=12
x=6

So in the original rectangle...the width is 6 m and the length is 8 m.


6. Let x=amount of water
10%(400) - 0x = 18%(400-x)

explanation: 400 is the amount of the salt solution so you multiply it to 10 because it's the concentration of salt in the solution.
0% on the water because the water is 0% salt.
400-x is the amount of the final salt solution because you were asked how much water must be evaporated. then you multiply it to the percentage...which is 18%.

then solution:

(400)(10) = 18(400-x)
4000 = 7200 - 18x
18x = 3200
x = 1600/9 or 177.778

so 177.778 L of water.

Sorry I couldn't answer numbers 2, 3 and 5.
2 and 3 involve squares...and i'm not good at squares.

and in number 5...
i dug through my notes in my freshman year...and i couldn't find any decent basis for investment problems.
sorry.

[CitrusFlower]

im no help, i hate math and im only in middle school, srry can't help you!looks confusing by the way

[oshirou]

this is a guess but for 1 and 7 i think it is 60mph.. and for number 4 it is x=6m.. w=6, l=8.. nyahhahha! v

[xskyi]

Tis made me hate math more......
But my math teacher call that Physic and algebra.
He is killing my brain! pushing in all that in grade 7 and 8. My god i will die soon.

Good luck.

[Bamboo]

5.) Total initial investment = $1200, which is the interest you want to earn back
1200 = I1 + I2, where I1 = 900(.06)t and I2 = 300(.08)t
1200 = 54t + 24t
1200 = 78t
t = 15.38461538 years
I don't know how many digits your teacher wants you to round to so I left them all on there.

[kappow]

question 2 is impossible. Eg 1+1=2 <--- the sum of the number 2+1squared[1]=3
and thats as low as u can go.... so IMPOSSIBLE!! and im working on question 3... but dont count on me getting it..

EDIT!! question 3 is impossible too. It says the difference between the number and its squared. Derrr obviously its impossible because all but one answer will be negative.. EG: 2-4=-2 3-9=-6 4-16=-12 and so on and so on.. 1-1=0 .. if someone can actually find numbers that fits into these questions den i would call u a geneous.

hope i helped!!