A car battery manufacturer claims that its car batteries last at least 4 years on average, under normal operating conditions. However, many consumers have experienced battery failure well before 4 years. A consumer advocacy group decided to investigate the company to determine if the company's claim about the average lifespan of their car batteries is exaggerated and misleading. A random sample of 54 batteries was collected and tested by the consumer advocacy group and the mean lifespan was found to be 3.96 years. Use the critical value method to test the hypothesis that the mean lifespan of this brand of car battery is less than 4 years, using a significance level of 5%. Assume that the standard deviation of the lifespans of all batteries produced by this company is known to be 0.7 years. State the null and alternative hypothesis for this test. H0: = > < p = p p p p > p < H1: = > < p = p p p p > p < Determine if this test is left-tailed, right-tailed, or two-tailed.

• left-tailed
• right-tailed
• two-tailed

Should the standard normal (z) distribution or Student's (t) distribution be used for this test?

• The standard normal (z) distribution should be used
• The Student's t distribution should be used

Determine the critical value(s) for this hypothesis test. Round the solution(s) to two decimal places. If more than one critical value exists, enter the solutions using a comma-separated list. Determine the test statistic. Round the solution to two decimal places.