Question

rezolvati va rog ex 6,7b si 8

Answer 1

2x/3y=1/2 =>
 => a)2x*2=3y =>x/y=3/4

=> b)y=4x/3  => (2x-y)/(x+y)=

=(2x-4x/3)/(x+4x/3) =
= ( (6x-4x)/3 )/((3x+4x)/3)=
=2x/7x=2/7

8) bile a,r,n
notam a+r+n= T (de la total)
a=30/100*T
r=20/100*a=>r=20/100 *(30/100*T)
n=32   

iar a+r+n=T  inlocuind obtinem:

(30/100  *T)  +( 20/100 *(30/100  *T) ) +32 =T <=>
(inmultim cu 100)
<=>30*T +6*T+3.200=100*T <=>
<=>36*T+3.200=100*t <=>T=3.200/64 <=>
<=>T=50 =>
=>a=30/100 *50 =15
     r=20/100*15 =3
     n=32  (verificare 15+3+32=18+32=50)

b) probabilitatea = (nr de cazuri favorabile)/ (nr de cazuri totale)

nr de cazuri favorabile = nr de bile albe =15
nr de cazuri totale  =T =50
=> p=15/50 =3/10 =0,3 (sau 30 %)

c)albe sunt 15
 rosii sunt 3

3 rosii.........................100%
15 albe ...........................x %
15*100=3*x => x=500%