# stat probability!! help me ~ = ]

• August 27th 2008, 09:08 PM
sinyoungoh
1st year stat probability!! help me ~ = ] (only few qs)
When mean=230 (avaerage people who arrived for their scheduled flights)
s.d= 30
the aircraft has seats for 305 passengers.

a) What is the probability that a randomly selected flight has enough seas available for all the people who turn up?
b)this flights goes everyday, During one year of operation, how many days, would you expect there to be more passengers than available seats? Justify ur anwser

c)what proportion of flights are at least half empty?
• August 31st 2008, 09:24 PM
chopet
a) assuming normal distribution,
$P(X \leq 305) = P(Z \leq {{305-230} \over 30 }) = P( Z \leq 2.5) = 1- 0.0062 = 0.9938$

b) 0.0062*365 = 2.265 = 3 (round up)

c) assuming normal distribution,
$P( X \leq {305 \over 2}) = P( Z \leq {{152.5 - 230} \over 30} ) = P (Z \leq -2.58) = 0.0049$

Can someone pls verify.