Class 11

Math

Algebra

Permutations and Combinations

The ways in which the time table for Monday be completed if there must be 5 lessons that day (Algebra, Geometry, Calculus,Trigonometry, Vectors) and Algebra and Geometry must not immediately follow each other are

- $72$
- $5!$
- $35!/2$
- $6!$

$→$ No. of ways in which the time table can be made, such that Algebra and Trigonometry follow each other $=2!×4!=48$

$→$ So, the no. of ways in which the time table can be made, such that Algebra and Trigonometry do not follow each other $=120−48=72$