Question

Calcium is essential to tree growth because it promotes the formation of wood and maintains cell walls. In​ 1990, the concentration of calcium in precipitation in a certain area was

0.11 milligrams per liter​ (mg/L). A random sample of 10 precipitation dates in 2007 results in the following data table. Complete parts​ (a) through​ (c) below.

​(a) State the hypotheses for determining if the mean concentration of calcium precipitation has changed since 1990.

Upper H0​:

▼

sigmaσ

muμ

pp

▼

=

greater than>

less than<

not equals≠

0.11 ​mg/L

Upper H1​:

▼

muμ

pp

sigmaσ

▼

equals=

not equals≠

less than<

greater than>

0.11 ​mg/L

Answer 1

We have to find the null and alternate hypothesis for the given case.

It is given in the question that the concentration of calcium in precipitation in a certain area was 0.11 milligrams per liter​ (mg/L) in 1990.

So, population mean =

We have to test whether mean concentration of calcium precipitation has changed since 1990, i.e. either decreased or increased. So, it is a two tailed hypothesis testing.

So, for null hypothesis we assume that the mean is equal to 0.11 and for allternate hypothesis, we assume that the mean is not equal to 0.11

we can write it as