Help with math ? please i suck in math...?

Question

1. There are 10 players in a chess tournament. Each player must play each other player one game. How many games will be played ?
a. 20
b. 30
c. 45
d. 55

2. How many liters of an 50 % solution must be mixed with 20 liters of a 75% acid solution in order to make a 60% acid solution ?

please explain
Thank you, answerers !
xD

how do i do it if i don't know it ? (icestar)

yes ikno i should study but this stupid hw is dued today at my 4 pm prep and my stupid teacher always look at my paper and say omg this wrong again ?
-_- sad, i kno

Answer 1

1. 45 is the answer.Hence C is correct
[Explanation-The first player will have to play 9 games,second one 8 games,third one 7 games and so on
hence the total no of games
=9+8+7+6+5+4+3+2+1=45 ]
2.Let x litres of 50% solution be mixed with 20 litres of 75% acid solution to make 20+x litres of 60% acid solution
By the problem
0.5x+0.75*20=0.6(20+x)
or 0.5x+15=12+0.6x
or,0.5x-0.6x=12-15
or,-0.1x= -3
or x= -3/=0.1=30
Therefore 30 litres of 50% solution is to be mixed

Answer 2

Call the first chess player A. He plays all nine opponents.
Second player B has already played 1 game so he has 8 more to play.
Third player C has already played 2 games, he has 7 more to play...and so on
add 9 and 8 and 7 and 6 and 5 and 4 and 3 and 2 and 1 the answer is 45 .
Don't know the answer to the second one, sorry.

Answer 3

For your first question the answer is C 45 why:
we have ten players : the first players play 09 times , but the second must only 8 , and the third must play only 7 and so one . So 9+8+7+6+5+4+3+2+1 equal 45.

Answer 4

Hey, I suck at math too, but I've tried not to let that fact stop me......;-)

Let's consider this on a player by player basis. The first player, in order to play a game with everyone else, has to play 9 games.

The second player has to play a *total* of 9 games, but wait......he's already played the first player, so only 8 additional games need to be set up! the third player has already played the first and second players, so to accommodate him, only 7 more games need to be played. thus, the pattern here is:

9+8+7+6+5+4+3+2+1.........

2) is a little more involved, mathematically.

We don't yet know the total amount of acid or water in the final solution, but we do know the *ratio* of acid to water;

60%[acid] / 40%[water] = 1.5;

or in other words,

acid / water = 1.5 .

In our original solution we had 75% acid / 25% water, so 20 liter of this stuff is comprised of 15 l of acid, and 5 l of water.

To this we add "x" amount of 50 : 50 solution, so the total amount of acid is:

acid = 15 + 0.5x (50% = 0.5).

The total amount of water is

water = 5 + 0.5x.

This makes the ratio we had at first

acid / water =

(15 + 0.5x) / (5 + 0.5x) = 1.5

I'll leave it up to you to solve this equation....

Good luck,
~W.O.M.B.A.T.

Answer 5

Answ 1: 10C2 = (10*9)/(1*2) = 45. The total combination is obtained by choosing 2 players out of 10. This uses the combination formula.

Answ 2: L liters has .5L acid solution. 20 liters has 15L acid solution.
When combined you have (L+20) liters with (15+.5L) acid.

You need to solve: .6(L+20) = (15+.5L)
This is how you will get your L. (btw, L should be 30.)

d:

Edit:
To help you gain knowledge and confidence, try solving many questions similar to your lessons. Some can help you on your assignments but realize the fact that during exams, you are on your own.

Answer 6

1. 10 C 2 = 45
meaning that from 10 people, u have 2 to play against each other... the function is in most of the scientific calculator nowadays...

2. 50% * V + 20 * 75 % = 60% (V+20) , provided that the percentage u are giving is in v/v%
from the eqt. above u can get 0.5V + 15 = 0.6V + 12
0.1 V = 3
V = 30 litre of it

Answer 7

1) The number of ways of selcting 2 people out of 10 people is, using combinatorial notation 10C2 = 10x9/2x1=45.

Answer 8

Umm, do your homework yourseld XP

You should study up instead of asking people on Y!A...