Select the correct answer from the drop-down menu. A box contains 20 lightbulbs, of which 5 are defective. If 4 lightbulbs are picked from the box randomly, the probability that at most 2 of them are defective is .

If 4 lightbulbs are picked from the box randomly, the probability that at most 2 of them are defective is

a.31/969

b.70/323

c.91/323

d.938/969

Step-by-step explanation:

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: