Question

exercitiul 2 va rog.

Answer 1

Răspuns:

Explicație pas cu pas:

$3\leq \dfrac{2(2x-5)}{3}-7< 29\dfrac{2}{3}, ~~~\dfrac{9}{3}\leq \dfrac{4x-10-21}{3}< \dfrac{29*3+2}{3}~|*3,~~~\\9\leq 4x-31< 89~|+31$

9+31≤4x<89+31, ⇒40≤4x<120 |:4, ⇒10≤x<30.

Deci, A=[10; 30).

A∩N={10, 11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29}

nr de elemente este n=29-10+1=20

nr de cazuri favorabile, m=4, pentru numerele 11,12,21,22.

Deci P=m/n=4/20=1/5=20/100=20%