The value of x can be found using the sine function.
sin 30 = x/8
8 (sin 30) = x
4 = x
The probability that none of the four have been vaccinated is
(1-0.63)^4 = 0.01874161
The probability that at least one has been vaccinated is the complement of this,
≈0.9813
7 in a half hrs everyday for 5 days equal 37.5 hrs
Y=10
x+3=y
x=7
I think this is the answer
hope it helps!