(a) There are ten places, where the boys can be seated. Now,
a2 cannot come at 9th and 10th positions otherwise condition is not fulfilled.
∴ Total number of ways the boys can be arranged in 8 places regarding
a2 = 8!
Similarly for
a5, he cannot be seated in first place and at the 10th place, then possible ways of arrangement = 8!
Now,
a7 cannot be seated on 1st and 2nd places, then possible number of ways = 8!
∴ Total number of w s = 8! + 8! + 8!
= 3 x 8 !
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