Question

Out of 15 items 4 arenot ingood conditionu areselected at random. Find the probability that
1.All areare not good.
2.Two are not good​

Answer 1

Answer:

1. 4c4/15c4=1/1305  

2.(4c2+11c2)/15c4=61/1365

Step-by-step explanation:

Answer 2

Answer:

1) 4 items are selected at random. Therefore, the probability of all not being good is:

$\frac{^{4}C_{4}}{^{15}C_{4}} \\ \\ \implies \frac{1}{\frac{15!}{4!11!} } \\ \\ \implies \boxed{\bold {\frac{1}{1365} }}$

2) The probability of 2 not being good is:

$\frac{^{4}C_{2}}{^{15}C_{4}} \\ \\ \implies \frac{\frac{4!}{2!2!} }{\frac{15!}{4!11!} } \\ \\ \implies \boxed{\bold {\frac{6}{1365} }}$