Hi Vivian,
The density function p(y)=c*(1/2) with the normalization that ∫p(y)dy from 0 to 2 =1 so c=1 and p(y)=1/2 for 0≤y≤2 and 0 for y>2.
So P(.5<y<1.3)= ∫.51.3p(y)dy=(1/2)*(1.3-.5)=.4
and P(y≥1.2)=∫1.2∞ p(y)dy=(1/2)*(2-1.2)=.4
Regards
Jim