Question

(9) In a box of floppy discs it is known that 95% will work. A sample of three of the discs is selected at random find the probability that
(i) none
(ii) 1
(iii) 2.
(iv) all 3 of the sample will work.
die​

Answer 1

Answer:

hence 95 is good. 5 are bad.

i

none

hence 5 C3 ÷ ( 100 C 3)

2nd

5c2 * 95 c 1 ÷ ( 100 C3)

3rd

5c1 × 95 c2 ÷ ( 100 c3)

4th

95 c3 ÷ (100 c 3 )