1. the life span of a fruit fly population is normally distributed with mean 21.
ID: 3154739 • Letter: 1
Question
1. the life span of a fruit fly
population is normally distributed with mean 21.3 days and standard deviation 3.8 days.
a). According to the empirical rule, approximately what percentage of the fly population has life
span between 13.7 and 28.9 day?
b).Find the probability that a randomly selected fruit fly has a life span exceeding 25.0 days?
c).If the life span of a fruit fly was considered to be in the 80th percentile of all such flies, how
long did it live?
d)A random sample of 40 fruit flies is selected. What is the probability that their average life
span is less than 21.0 days?
e).A random sample of 8 fruit flies is selected. What is the probability that at least one of them
has a life span exceeding 21.3 days?
Explanation / Answer
a)
According to the empirical rule, approximately 95% of the fly population has life span between 21.3-2*3.8=13.7 and 21.3+2*3.8=28.9 day
b)For X=25, z=(x-mu)/sigma=(25-21.3)/3.8=0.97
P(X>25)=P(z>0.97)=1-P(z<0.97)=1-0.8340=0.166
d)The standard error of mean=3.8/rot over 40=0.6
For X=21, z=(21-21.3)/0.6=-0.5
P(X<21)=P(z<-0.5)=0.3085
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.