Question

# You want to estimate the average starting salary of San Jose graduates. You call a random...

You want to estimate the average starting salary of San Jose graduates. You call a random sample
of 200 students who graduated in the last two years. After collecting the data, you are about to
calculate the 95% confidence interval when you remember that incomes
are skewed to the right. Isn’t a 95% confidence interval based on a normal curve? Was all your
work in vain? Explain, making reference to the assumptions required for confidence intervals to
be valid.

SoL

For constructing confidence interval for mean

the sample to simple independent random sample

and sample follows normal distribution (n>30)

as for large smaple (n>30),according to central limit theorem,sample follows normal distribution

Independence Assumption

Random sampling

Sample size condition: n > 30

Here n=200

so given sample follows normal distribution as n>30

And given sample is random sample

95% confidence interval based on a normal curve so work is not in vain

we can calculate 95% confidence interval for average starting salary of San Jose graduates based on sample of 200  students who graduated in the last two years

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