Question

A bag contains 3 black, 3 white and 2 red balls. Three balls are drawn without replacement one-by-one. The probability that the third ball is red, is

• A. $\theta ={\sin }^{-1}\left[\frac{\lambda }{3d}\right]$
• B. $V=\frac{Q}{C}=Q.\frac{d}{{\epsilon }_{0}A}$
• C. $\eta =1-\frac{T_2}{T_1}=1-\frac{500}{800}$
• D. $=\frac{3}{8}=0.375$

Answer 1

Answer: (D)

Three possible cases arise
$IIst$ draw
$IInd$ draw
$IIIrd$ draw
Red Non-red Non-red
Non-red Red Non-red
Red Red Red
$\therefore$ Required probability $=\frac{2}{8}\times \frac{6}{7}\times \frac{1}{6}+\frac{6}{8}\times \frac{2}{7}\times \frac{1}{6}+\frac{6}{8}\times \frac{5}{7}\times \frac{2}{6}$ $=\frac{2}{56}+\frac{2}{56}+\frac{10}{56}=\frac{14}{56}$