Pregunta: Acid rain, caused by the reaction of certain air pollutants with rainwater, appears to be a growing problem in the northeastern United States. (Acid rain affects thesoil and causes corrosion on exposed metal surfaces). Pure rain falling through clean air registers a PH value of 5.7 (PH is a measure of acidity: 0 is acid; 14 isalkaline). Suppose water

Acid rain, caused by the reaction of certain air pollutants with rainwater, appears to be a growing problem in the northeastern United States. $($Acid rain affects the

soil and causes corrosion on exposed metal surfaces$).$ Pure rain falling through clean air registers a $PH$ value of $5\mathrm{.}7($PH is a measure of acidity: $0$ is acid; $14$ is

alkaline$).$ Suppose water samples from $40$ rainfalls are analyzed for $PH,$ and the mean $(x)$ and $5$ are equal to $3\mathrm{.}7$ and $0\mathrm{.}5,$ respectively.

La lluvia acida. causada por la reacci$ó$n de ciertos contaminantes con la lluvia, parece ser un problema creciente en el noreste de los Estados Unidos. $($La lluvia acida

afecta el terreno y causa corrosi$ó$n en las superficies de metal expuestas. Lluvia pura cayendo a trav$é$s de aire limpio registra con un valor de PH de $5\mathrm{.}7($PH es la

medida de acidez: $0$ para acido; $14$ para alcalino.$)$ Suponga que se analizan muestras de $40$ lluvias para el $PH,$ y el promedio de $x$ es $3\mathrm{.}7y$ el valor de $s$ es $0\mathrm{.}5,$

respectivamente.

What is true of this situation? $($Choose all that apply.$)$

$¿$Qu$é$ es cierto en esta situaci$ó$n$?($Escoja todas las que apliquen.$)$

The sample of $40$ is a very small sample. La muestra de $40$ es una muestra bien peque$ñ$a$.$

The sample of $40$ is considered a large sample. La muestra de $40$ se considera una muestra grande.

The standard deviation of the population is known. La desviaci$ó$n est$á$ndar de la poblaci$ó$n se conoce.

The $2-$side confidence interval includes the value of $Z(\frac{\alpha }{2}).$ El intervalo de confianza de dos colas incluir$á$ el valor de $Z(\frac{\alpha }{2}).$