Answer:
Step-by-step explanation:
Total no. of goods, n = 200
no. of defective units in the goods, d = 20
hence the no. of proper units,
g = n-d
g = = 200-20
g = 180
a)
ways in which a vending company buys fifteen of these microwaves and receive no defective units be:
[tex]^{180}C_{15}=\frac{180!}{15!\times (180-15)!}[/tex]
[tex]\approx 2.83\times 10^{21}[/tex]
b)
ways in which a vending company buys fifteen of these microwaves and receive exactly two defective units be:
[tex]^{20}C_2\times ^{180}C_{13}=\frac{20!}{2!\times (20-2)!} \times \frac{180!}{13!\times (180-13)!}[/tex]
[tex]\approx 190\times (2.146\times 10^{19})[/tex]
[tex]\approx 4.076\times 10^{21}[/tex]
c)
ways in which a vending company buys fifteen of these microwaves and receive at least one defective units be:
[tex]^{20}C_{1}\times ^{199}C_{14}=\frac{20!}{1!\times (20-1)!} \times \frac{199!}{13!\times (199-13)!}[/tex]
[tex]\approx 20\times (8.258\times 10^{19})[/tex]
[tex]\approx 1.652\times 10^{21}[/tex]
