Questions: An oceanographer claims that the mean dive duration of a North Atlantic right whale is 11.3 minutes. A random sample of 36 dive durations has a mean of 12.4 minutes and a standard deviation of 2.1 minutes. At α=0.10 is there enough evidence to reject the oceanographer's claim? Complete parts (a) through (d) below. Assume the population is normally distributed.
(a) Identify the claim and state H0 and Ha.
H0: μ = 11.3 Ha: μ ≠ 11.3
(Type integers or decimals. Do not round.)
The claim is the hypothesis.
(b) Use technology to Find the standardized test statistic, t
t=
(Round to two decimals.)
(c) Obtain the P-value
P=
(Round to three decimal places as needed.)
(d) Decide whether to reject or fail to reject the null hypothesis.
H0 because the P-value greater than α.
(e) Interpret the decision in the context of the original claim.
There enough evidence at the % level of significance to the claim that the mean dive duration of a North Atlantic right whale is minutes.
Transcript text: An oceanographer claims that the mean dive duration of a North Atlantic right whale is 11.3 minutes. A random sample of 36 dive durations has a mean of 12.4 minutes and a standard deviation of 2.1 minutes. At $\alpha=0.10$ is there enough evidence to reject the oceanographer's claim? Complete parts (a) through (d) below. Assume the population is normally distributed.
(a) Identify the claim and state $\mathrm{H}_{0}$ and $\mathrm{H}_{\mathrm{a}}$.
\[
H_{0}
\]
$\square$
$\square$ 11.3 $\mathrm{H}_{\mathrm{a}}$ : $\square$
$\square$ 11.3
(Type integers or decimals. Do not round.)
The claim is the $\square$ hypothesis.
(b) Use technology to Find the standardized test statistic, t
\[
t=
\]
$\square$
(Round to two decimals.)
(c) Obtain the $P$-value
\[
P=
\]
$\square$
(Round to three decimal places as needed.)
(d) Decide whether to reject or fail to reject the null hypothesis.
$\square$ $\mathrm{H}_{0}$ because the P-value $\square$ greater than $\alpha$.
(e) Interpret the decision in the context of the original claim.
There $\square$ enough evidence at the $\square$ \% level of significance to $\square$ the claim that the mean dive duration of a North Atlantic right whale is $\square$ minutes.
Solution
Solution Steps
Step 1: Identify the Hypotheses
The oceanographer claims that the mean dive duration of a North Atlantic right whale is \( \mu = 11.3 \) minutes. We can set up our hypotheses as follows:
\[
H_0: \mu = 11.3 \quad \text{(null hypothesis)}
\]
\[
H_a: \mu \neq 11.3 \quad \text{(alternative hypothesis)}
\]
The claim is the null hypothesis.
Step 2: Calculate the Test Statistic
To determine if we can reject the null hypothesis, we calculate the standardized test statistic \( Z_{test} \). The standard error \( SE \) is calculated as:
\[
SE = \frac{\sigma}{\sqrt{n}} = \frac{2.1}{\sqrt{36}} = 0.35
\]
The test statistic is then calculated using the formula:
\[
Z_{test} = \frac{\bar{x} - \mu_0}{SE} = \frac{12.4 - 11.3}{0.35} = 3.1429
\]
Step 3: Calculate the P-value
For a two-tailed test, the P-value is calculated as:
\[
P = 2 \times (1 - T(|z|)) = 0.0017
\]
Step 4: Decision on the Null Hypothesis
We compare the P-value to the significance level \( \alpha = 0.10 \):
Since \( P = 0.0017 < \alpha \), we reject the null hypothesis \( H_0 \).
Final Answer
There is enough evidence at the \( 10\% \) level of significance to reject the claim that the mean dive duration of a North Atlantic right whale is \( 11.3 \) minutes.