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Who uses YouTube more: men or women? Based on two independent SRSs of 25 women and 28 men we will estimate the difference between their corresponding mean by means of a 90% CI. The value of the multplier should be:

1.318

1.960

1.711

1.703

2.000

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If you take random samples of the same size repeatedly from the same population, and for each sample you construct a 95% confidence interval for the population mean, then about 95% of the intervals should contain the population mean.

True

False

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Recent data from a sample of 100 patients shows that on average it takes about 6 ± 2 months to see a dermatologist in BC. Suppose we want to construct a new CI with margin of error 1 month. Then we need to:

decrease the confidence level to 1 month.

take a new sample of 25 patients.

decrease the precision to 1 month.

take a new sample of 400 patients.

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When one changes the significance level of a hypothesis test from 0.01 to 0.05, which of the following will happen?

The chances that the null hypothesis is true changes from 0.01 to 0.05.

The test becomes less stringent to reject the null hypothesis.

The chances of committing a Type II error changes from 0.05 to 0.01.

The chances of committing a Type I error changes from 0.05 to 0.01.

The test becomes more stringent to reject the null hypothesis.

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In 2007, the ALOS (Average Length of Stay) in the US was 5.5 days. This means that about 50% of inpatient hospital stays in the US in 2007 lasted less than 5.5 days.

FALSE

✅

TRUE

❌

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The expected value of a discrete random variable X can be computed by means of

The probability density function of X