1. CNN/Money reports that the mean cost of a speeding ticket in the United States, including court fees, was $150 in 2010. A local citizen’s organization believes that this amount has increased, so they collect data from a random sample of 160 drivers who have been fined for speeding in the past year. The average was $154.00 with a standard deviation of $17.54. The distribution is slightly right skewed with no outliers.
Step 1: Write the null and alternative hypotheses. Determine if the test is one-tailed, or two-tailed and whether you should a z or a t test.
Step 2: Check the conditions.
Step 3: Calculate the test statistics and find the P-value.
Step 4: State the conclusion at the =0.05 significance level.
Below are the null and alternative Hypothesis,
Null Hypothesis, H0: μ = 150
Alternative Hypothesis, Ha: μ > 150
t-test, right tailed
sample is sufficiently large and data is assumed to be normally distributed
Test statistic,
t = (xbar - mu)/(s/sqrt(n))
t = (154 - 150)/(17.54/sqrt(160))
t = 2.885
P-value Approach
P-value = 0.0022
As P-value < 0.05, reject the null hypothesis.
1. CNN/Money reports that the mean cost of a speeding ticket in the United States, including...