What is the probability that everyone who shows up will have a seat if I accept reservations for 25, have 23?

I have 23 seats.
Take reservations for 25.
90% of reservations show up.
Probability that everyone who shows up will have a seat?

np = 25(.9) = 22.5
npq = 2.25
StdDv = sqrt (2.25) = 1.5

Prob (N = 25): Consider Z-score for (25 - 23) / 1.5 = 2 / 1.5 = 1.333.
Prob (N = 24): Consider Z-score for (24 - 23) / 1.5 = 1 /1.5 = 0.667

Answer = 100% - Prob (N=25) - Prob (N=24)

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2 Responses to “What is the probability that everyone who shows up will have a seat if I accept reservations for 25, have 23?”

s.talalhussain on October 25th, 2009 at 11:56 pm

90 percent of 25 is … 22.5 …
so u have 23 seats and 22.5 show up… that is all the people that come will have a seat…
100% probabilty that every one gets a seat
answerd upto best i understood
References :
zeuz on October 26th, 2009 at 12:14 am

np = 25(.9) = 22.5
npq = 2.25
StdDv = sqrt (2.25) = 1.5

Prob (N = 25): Consider Z-score for (25 - 23) / 1.5 = 2 / 1.5 = 1.333.
Prob (N = 24): Consider Z-score for (24 - 23) / 1.5 = 1 /1.5 = 0.667

Answer = 100% - Prob (N=25) - Prob (N=24)
References :

desdelaxarxa.net