Questions
A table has provision for 7 seats, 4 being on one side facing the window and 3 being on the opposite side. The number of ways in which 7 people can be seated at the table if 2 people, X and Y, must sit on the same side, is
detailed solution
Correct option is B
When X and Y sit on the side facing the window—First, we have to select 2 persons for the side facing the window and 3 for the opposite side from the remaining 5. The number of selections for this is equal to 5C2×3C3.For each of the selections, the number of arrangements = 4! × 3!.∴ The number of ways to sit when X, Y are on the side facing the window =5C2×3C3×4!×3!.When X and Y sit on the other sideAs before, the number of ways to sit=5C1×4C4×4!×3!∴ Required number of ways=5C2×3C3×4!×3!+5C1×4C4×4!×3!=5×42×1×24×6+5×1×24×6=2160Similar Questions
Let be a set containing elements. The number of reflexive relations that can be defined on is
799 666 8865
support@infinitylearn.com
6th Floor, NCC Building, Durgamma Cheruvu Road, Vittal Rao Nagar, HITEC City, Hyderabad, Telangana 500081.
JEE Mock Tests
JEE study guide
JEE Revision Notes
JEE Important Questions
JEE Sample Papers
JEE Previous Year's Papers
NEET previous year’s papers
NEET important questions
NEET sample papers
NEET revision notes
NEET study guide
NEET mock tests