A bag contains 20 tickets numbered with 1 to 20. Three tickets are drawn. The probability that ticket number 7 is definitely included and ticket number 18 is not included is-

Asked by RIZWAN YASIN | 8th Dec, 2013, 11:42: PM

Expert Answer:

Total number of ways selecting three tickets out of 20 is 20C3.
 
The number of ways in which ticket 7 is definitely included and ticket number 18 is not included out of 18 cards is 18C2.
 
Therefore, the probability that ticket number 7 is definitely included and ticket number 18 is not included is -

Answered by Vimala Ramamurthy | 9th Dec, 2013, 08:59: AM

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