In a shipment of 20 smartphones, 2 are defective. How many ways can a quality control inspector randomly test 4 smartphones, of which 2 are defective?

The quality control inspector can add 4 randomly selected smartphones from the rest of 20-2 = 18 smartphones.

And 816 ways

Step-by-step explanation:

the system of inequalities is

step-by-step explanation:

step 1

find the equation of the dashed line

we have the points

(0,0) and (3,1)

the line passes through the origin, so, is a direct variation

find the slope

the equation of the dashed line is

the solution of the inequality a s the shaded area above the dashed line

therefore

the equation of the inequality a is

step 2

find the equation of the solid line

we have the points

(4,0) and (0,4)

find the slope

the equation of the solid line is

the solution of the inequality b s the shaded area below the solid line

therefore

the equation of the inequality b is

step 3

the system of inequalities is

29933333.33

step-by-step explanation: