A researcher is interested in estimating the mean BMI of adults in UAE. He selected a random sample of 20 adults which yielded a mean of 24.5 kg/m and a standard deviation of 1.3kg/m2. He believes that the BMI of adults is approximately normally distributed. Which distribution should he use to construct the confidence interval? C t distribution with 19 degrees of freedom C Neither t nor standard normal distribution. O t distribution with 20 degrees of freedom O Standard normal distribution

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