question_answer

There are 10 girls and 8 boys in a classroom including Mr Ravi, Ms Rani and Ms Radha. A list of speakers consisting of 8 girls and 6 boys has to be prepared Mr Ravi refuses to speak. If Mr Ravi refuses to speak, if Ms Rani is a speaker. The number of ways the list can be prepared is

A)  202                            

B)  308  

C)  567                            

D)  952

Correct Answer: B

Solution :

 10 girls and 8 boys (Selected 8 girls and 6 boys) Mr Ravi refuses to speak, if Ms Rani is a speaker. Mrs Rani refuses to speak, if Ms Radha is a speaker. Let       \[=-0.25\times {{10}^{-3}}\,Wb\] Mr Ravi is a speaker \[e=-\frac{\Delta \phi }{\Delta t}\]Ms Rani is a speaker  \[=\frac{0.25\times {{10}^{-3}}Wb}{0.05\,s}=5\times {{10}^{-3}}V\] Ms Radha is a speaker Set satisfying the given condition is represented in the Venn diagram \[=100\,\left( \frac{\Delta \phi }{\Delta t} \right)\] Number of ways of preparing the list \[=5\times {{10}^{-3}}\times 100=0.5\,\,V\] \[R=v\sqrt{\frac{2h}{g}}\]