Get Answers to all your Questions

header-bg qa

In how many ways can a Quality Analyst team of 10 members be made from 18 experts such that 5 English experts must never be included in the team?

Option: 1

1360


Option: 2

1162


Option: 3

1287


Option: 4

Cannot be determined


Answers (1)

best_answer

Note the following:

  • The formula for the combination for the selection of the \mathrm{ x} items from the \mathrm{ y} different items is \mathrm{ ={ }^y \mathrm{C}_x=\frac{y !}{x !(y-x) !} }

 

  • The restricted combination for the selection of the \mathrm{ r } items from the \mathrm{ n } different items with \mathrm{ \mathrm{k} } particular things always excluded is ={ }^{\mathrm{n}-\mathrm{k}} \mathrm{C}_{\mathrm{r}}

Since 5 English experts must never be included in the Quality Analyst, the following is evident.

  • The number from which the restricted combination is to be made is

          \mathrm{=n-k=18-5=13.}

  • The number with which the restricted combination is to be made is

           \mathrm{=r-k=10-5=5}

Therefore, the required restricted combination is

\mathrm{ ={ }^{n-k} \mathrm{C}_{\mathrm{r}} }
\mathrm{ ={ }^{13} \mathrm{C}_5 }

\mathrm{=\frac{13!}{8!5!}}

\mathrm{=1287}
 

Posted by

Devendra Khairwa

View full answer

JEE Main high-scoring chapters and topics

Study 40% syllabus and score up to 100% marks in JEE