A random sample of $n=18$ school water bottles has $\bar{x}=742$ mL and $s=88$ mL; $\sigma$ is unknown. For a 95% one-sample t interval for $\mu$, how many degrees of freedom does $t^{\ast }$ use?

A random sample of $n=25$ students has $\bar{x}=18.4$ minutes reading and $s=3.5$ minutes. For a 95% one-sample t interval, what is the standard error of $\bar{x}$ to two decimals?

A clinic samples $n=16$ visits with $\bar{x}=12.6$ minutes, $s=3.2$ minutes, and $t^{\ast }=2.131$. What is the 95% confidence interval for $\mu$, rounded to one decimal?

A factory samples $n=36$ batteries with $\bar{x}=48.20$ hours, $s=6.00$ hours, and $t^{\ast }=2.030$. Find the 95% confidence interval for $\mu$ to two decimals.

To estimate the mean mass of apples from an orchard, a random sample of $n=22$ apples has $\bar{x}=156$ g and $s=18$ g. For a 90% t interval, what degrees of freedom are used for $t^{\ast }$?

A school samples $n=25$ backpacks with $\bar{x}=6.80$ kg, $s=1.50$ kg, and $t^{\ast }=2.064$. What is the 95% confidence interval for the mean backpack mass, to two decimals?

A random sample of $n=49$ cereal boxes has $\bar{x}=506$ g and $s=14.0$ g. For a 99% one-sample t interval, compute the standard error of $\bar{x}$ to two decimals.

A farm samples $n=9$ pumpkins with $\bar{x}=4.6$ kg, $s=1.2$ kg, and $t^{\ast }=2.306$. What is the 95% confidence interval for the mean pumpkin mass, rounded to one decimal?

A random sample of $n=31$ athletes has $\bar{x}=2.14$ L of water used and $s=0.42$ L. For a 95% t interval for the population mean, how many degrees of freedom determine $t^{\ast }$?

A bus system samples $n=20$ delays with $\bar{x}=7.4$ minutes, $s=2.8$ minutes, and $t^{\ast }=2.093$. Give the 95% confidence interval for mean delay, rounded to one decimal.

A library samples $n=64$ books with $\bar{x}=420$ g, $s=32$ g, and $t^{\ast }=2.000$. What 95% confidence interval estimates the mean book mass, rounded to the nearest gram?

A lab samples $n=36$ beakers filled by a dispenser, with $\bar{x}=251.0$ mL and $s=9.0$ mL. For a 95% one-sample t interval, what is the standard error to two decimals?

A random sample of $n=12$ soil plots has $\bar{x}=38.5$ kg of compost and $s=7.4$ kg; $\sigma$ is unknown. For a 90% t interval, what degrees of freedom should be used?

A city samples $n=28$ tree heights with $\bar{x}=5.6$ m and $s=1.1$ m, and $\sigma$ is unknown. Which 95% interval procedure fits this situation?

A coach samples $n=30$ runners with $\bar{x}=24.8$ minutes, $s=3.0$ minutes, and $t^{\ast }=2.045$. Estimate the mean 5 km time with a 95% confidence interval to one decimal.

A manufacturer samples $n=16$ metal rods with $\bar{x}=102.4$ cm and $s=4.5$ cm. Historical data show $\sigma =4.0$ cm. Which 95% interval procedure should estimate $\mu$?

A random sample of $n=40$ tomatoes has $\bar{x}=118$ g and $s=21$ g. For a 95% one-sample t confidence interval for the population mean mass, what is the degrees of freedom?

A nursery samples $n=10$ watering cans with $\bar{x}=5.20$ L and $s=0.90$ L. For a 95% one-sample t interval, what is the standard error of $\bar{x}$ to two decimals?

A pharmacy samples $n=50$ tablets with $\bar{x}=250.0$ mg, $s=10.0$ mg, and $t^{\ast }=2.010$. What is the 95% confidence interval for mean tablet mass, to one decimal?

An aquarium samples $n=21$ fish with $\bar{x}=8.6$ cm and $s=1.4$ cm, but the population $\sigma$ is not known. Which 99% confidence interval procedure should be used?