A) There are how many years ? Ans. Not 21 nor 10 B) There are how many years ? X

Question

A) There are how many years ? Ans. Not 21 nor 10 B) There are how many years ? X) 2.3.26 Question Help A study concluded that following 7 simple health rules can extend a man's life by 11 years on the average and a woman's life by 7 years. These 7 rules are as follows: no smoking, get regular exercise, use alcohol only in moderation, get 7 to 8 hours of sleep, maintain proper weight, eat breakfast, and do not eat between meals. In how many ways can a person adopt 5 of these rules to follow (a) if the person presently violates 5 of the 7 rules? (b) if the person always eats breakfast? (a) There are ways.

Explanation / Answer

a) 7C5 = 7! / (5! 2!) = 7x6x5x4x3x2x1/{(5x4x3x2x1)(2x1)} = 42/2 = 21 ways

b)always eats breakfast >> 1 rules are used.
7-1=1 rule left to choose in total

Only violate 4 out of the 5 rules
5C4 = 5!/(4!1!) = 5 ways

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