Question

A shipment of 10 microwave ovens contains 3 defective units. A restaurant buys three of these unitsWhat is the probability of the restaurant buying at least two The probability of the restaurant buying at least two nondefective units? The probability of the restaurant buying atleast two nondefective unit is

Answer 1

Answer )

Probability is given by favorable/total

Total = 10

Defective = 3

Non defective = 7

We need to find P(at least 2 non defective)

That is we have two cases

Case 1

P(2 non defective)

P(first non defective) = 7/10

P(second non defective) = 6/9 (as first is already considerd we are now left with 6 non defective,9 in total and 3 defective)

P(third defective) = 3/8

P(2 non defective and one defective) = (7/10)*(6/9)*(3/8) = 0.175

Case 2

P(3 non defective)

= (7/10)*(6/9)*(5/8)

= 0.29166666666

Probability = case 1 + case 2 = 0.4667