Someone plz help me i really need help with this
2 answers:
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Answer:
1,539
Step-by-step explanation:
Using Simple Random Sampling in an infinite population (this is such a large population that we do not know the exact number) we have that the sample size should be the nearest integer to
where
<em>Z= the z-score corresponding to the confidence level, in this case 90%, so Z=1.645 (this means that the area under the Normal N(0,1) between [-1.645,1.645] is 90%=0.9) </em>
<em>p= the proportion of young urban people (ages 21 to 35 years) who go to at least 3 concerts a year= 35% = 0.35 </em>
<em>q = 1-p = 0.65 </em>
<em>e = the error proportion = 2% = 0.02 </em>
Making the calculations
So, the sample size should be 1,539 young urban people (ages 21 to 35 years)
Answer:
a) E(X)=1
b) σ=1
c) P(X>1)=0.368
d) P(2<X<5)=0.128
Step-by-step explanation:
We have X: "the time between two successive arrivals at the drive-up window of a local bank", exponentially distributed with λ = 1.
a) We have to compute the expected time between two successive arrivals.
The expected value for X as it is exponentially distributed is:
b) We have to compute the standard deviation of X.
The standard deviation is calculated as:
c) The probability that X is larger than 1 (P(X>1))
We can express the probability as:
d) The probability that X is between 2 and 5 (P(2<X<5))