Question

Among 12 metal parts produced in a machine shop, 3 are defective. If a random sample of three of these metal parts is selected, find the probability that this sample will contain at least two defectives.

Answer 1

Explanation:

`reqd.~probability=(3c_(2) +9c_(1) )/(12c_(3) ) +(3c_(3) )/(12c_(3) ) \\=((3 * 2)/(2 * 1) +(9)/(1) )/((12 * 11 * 10)/(3 *2*1) ) +((3*2*1)/(3*2*1) )/((12 *11*10)/(3 *2*1) ) \\=(3+9)/(220) +(1)/(220) \\=(13)/(220)`