The security system at an it office is composed of 10 computers of which exactly four are working. to check whether the system is functional, the officials inspect four of the computers picked at random (without replacement). the system is deemed functional if at least three of the four computers inspected are working. let the probability that the system is deemed functional be denoted by p. then 100p =
(a) 11.85
(b) 12.80
(c) 10.70
(d) 11.55

11.9%

Step-by-step explanation:

Total ways to pick 4 computers = 10×9×8×7

Total ways that at least three computers are fine =  

Total ways that all 4 are fine + Total ways any 3 are fine

Total ways that all 4 are fine = 4×3×2×1

Total ways three are fine = 1st is Not working and other 3 working +  

                           2nd is Not working and other 3 working +  

                           3rd is Not working and other 3 working +  

                           4th is Not working and other 3 working +  

                        = 6×4×3×2 + 4×6×3×2 + 4×3×6×2 + 4×3×2×6

                        = 6×4×3×2×4

The probability = Total ways that at least three computers are fine /  

                 Total ways to pick 4 computers  

               =  (4×3×2×1 + 6×4×3×2×4) / (10×9×8×7)

               = (4×3×2×25) / (10×9×8×7)

               = 11.9%

step-by-step explanation:

one of the most important purposes of surface treatment is to alter surface properties according to the requirement of specific applications. for example, hydrophobic coating has been utilized on windshield and eyeglasses. gold atom monolayer on substrate has become a popular surface bioconjugation strategy.  

knlknlkkn

step-by-step explanation: