Answer:
45 of the phones are black smartphones.
Step-by-step explanation:
We sould this question treating these probabilities as Venn events.
I am going to say that:
Event A: Smartphone.
Event B: Black.
450 are smartphones and 270 are black.
This means that [tex]A = 450, B = 270[/tex].
225 phones are not black and not a smartphone
This means 900 - 225 = 675 are either black or a smartphone, that is, [tex](A \cup B) = 675[/tex]
How many of the phones are black smartphones?
This is:
[tex](A \cap B) = A + B - (A \cup B)[/tex]
Considering the values we found:
[tex](A \cap B) = A + B - (A \cup B) = 450 + 270 - 675 = 45[/tex]
45 of the phones are black smartphones.
